Add and heartbeat to engine exchangeTransitionConfigurationV1 method

[g11tech]

Motivation
Engine expects every now and then a call to exchange transition config otherwise it warns the users as

WARN [08-14|10:16:25.522] Post-merge network, but no beacon client seen. Please launch one to follow the chain! 
WARN [08-14|10:16:55.526] Post-merge network, but no beacon client seen. Please launch one to follow the chain! 

even if the requests are going at the engine endpoint

Add and heartbeat to engine exchangeTransitionConfigurationV1 method to notify and match merge params with the EL.

On this PR, the EL stops complaining about the CL not being connected, manually tested and verified. (and gives this warning once lodestar is stopped, so as to confirm it saw CL connection/heartbeat:

WARN [08-14|10:27:25.603] Previously seen beacon client is offline. Please ensure it is operational to follow the chain!

Closes #4364

[github-actions]

Performance Report

✔️ no performance regression detected

Full benchmark results

Benchmark suite	Current: fe03f4f	Previous: 20edb58	Ratio
getPubkeys - index2pubkey - req 1000 vs - 250000 vc	2.3281 ms/op	2.3467 ms/op	0.99
getPubkeys - validatorsArr - req 1000 vs - 250000 vc	80.026 us/op	82.711 us/op	0.97
BLS verify - blst-native	1.8533 ms/op	2.7172 ms/op	0.68
BLS verifyMultipleSignatures 3 - blst-native	3.8012 ms/op	5.5908 ms/op	0.68
BLS verifyMultipleSignatures 8 - blst-native	8.1725 ms/op	11.947 ms/op	0.68
BLS verifyMultipleSignatures 32 - blst-native	29.640 ms/op	43.367 ms/op	0.68
BLS aggregatePubkeys 32 - blst-native	40.936 us/op	59.241 us/op	0.69
BLS aggregatePubkeys 128 - blst-native	157.15 us/op	230.22 us/op	0.68
getAttestationsForBlock	175.74 ms/op	174.90 ms/op	1.00
isKnown best case - 1 super set check	441.00 ns/op	512.00 ns/op	0.86
isKnown normal case - 2 super set checks	419.00 ns/op	477.00 ns/op	0.88
isKnown worse case - 16 super set checks	429.00 ns/op	456.00 ns/op	0.94
CheckpointStateCache - add get delete	9.4250 us/op	9.4510 us/op	1.00
validate gossip signedAggregateAndProof - struct	4.2717 ms/op	5.7184 ms/op	0.75
validate gossip attestation - struct	2.0350 ms/op	2.6761 ms/op	0.76
altair verifyImport mainnet_s3766816:31	4.6056 s/op	5.7110 s/op	0.81
pickEth1Vote - no votes	2.1545 ms/op	2.2622 ms/op	0.95
pickEth1Vote - max votes	25.323 ms/op	23.302 ms/op	1.09
pickEth1Vote - Eth1Data hashTreeRoot value x2048	11.574 ms/op	15.513 ms/op	0.75
pickEth1Vote - Eth1Data hashTreeRoot tree x2048	24.636 ms/op	19.848 ms/op	1.24
pickEth1Vote - Eth1Data fastSerialize value x2048	1.7601 ms/op	1.5506 ms/op	1.14
pickEth1Vote - Eth1Data fastSerialize tree x2048	13.702 ms/op	12.698 ms/op	1.08
bytes32 toHexString	1.1060 us/op	1.0490 us/op	1.05
bytes32 Buffer.toString(hex)	729.00 ns/op	733.00 ns/op	0.99
bytes32 Buffer.toString(hex) from Uint8Array	891.00 ns/op	935.00 ns/op	0.95
bytes32 Buffer.toString(hex) + 0x	713.00 ns/op	739.00 ns/op	0.96
Object access 1 prop	0.36300 ns/op	0.35200 ns/op	1.03
Map access 1 prop	0.29000 ns/op	0.31100 ns/op	0.93
Object get x1000	17.333 ns/op	15.060 ns/op	1.15
Map get x1000	1.0160 ns/op	1.0330 ns/op	0.98
Object set x1000	116.69 ns/op	105.15 ns/op	1.11
Map set x1000	70.369 ns/op	76.358 ns/op	0.92
Return object 10000 times	0.37550 ns/op	0.41510 ns/op	0.90
Throw Error 10000 times	5.8760 us/op	6.9526 us/op	0.85
enrSubnets - fastDeserialize 64 bits	2.7410 us/op	2.8940 us/op	0.95
enrSubnets - ssz BitVector 64 bits	891.00 ns/op	839.00 ns/op	1.06
enrSubnets - fastDeserialize 4 bits	407.00 ns/op	410.00 ns/op	0.99
enrSubnets - ssz BitVector 4 bits	881.00 ns/op	803.00 ns/op	1.10
prioritizePeers score -10:0 att 32-0.1 sync 2-0	93.897 us/op	104.70 us/op	0.90
prioritizePeers score 0:0 att 32-0.25 sync 2-0.25	133.67 us/op	156.42 us/op	0.85
prioritizePeers score 0:0 att 32-0.5 sync 2-0.5	252.24 us/op	260.90 us/op	0.97
prioritizePeers score 0:0 att 64-0.75 sync 4-0.75	391.51 us/op	575.94 us/op	0.68
prioritizePeers score 0:0 att 64-1 sync 4-1	460.86 us/op	624.34 us/op	0.74
RateTracker 1000000 limit, 1 obj count per request	199.32 ns/op	209.58 ns/op	0.95
RateTracker 1000000 limit, 2 obj count per request	154.73 ns/op	141.01 ns/op	1.10
RateTracker 1000000 limit, 4 obj count per request	132.36 ns/op	129.81 ns/op	1.02
RateTracker 1000000 limit, 8 obj count per request	121.21 ns/op	107.99 ns/op	1.12
RateTracker with prune	4.5750 us/op	4.3000 us/op	1.06
array of 16000 items push then shift	3.1707 us/op	5.1064 us/op	0.62
LinkedList of 16000 items push then shift	26.354 ns/op	32.528 ns/op	0.81
array of 16000 items push then pop	232.40 ns/op	222.69 ns/op	1.04
LinkedList of 16000 items push then pop	22.037 ns/op	25.470 ns/op	0.87
array of 24000 items push then shift	4.5729 us/op	7.9289 us/op	0.58
LinkedList of 24000 items push then shift	28.078 ns/op	30.659 ns/op	0.92
array of 24000 items push then pop	213.45 ns/op	220.28 ns/op	0.97
LinkedList of 24000 items push then pop	22.111 ns/op	24.862 ns/op	0.89
intersect bitArray bitLen 8	11.629 ns/op	14.840 ns/op	0.78
intersect array and set length 8	171.96 ns/op	170.04 ns/op	1.01
intersect bitArray bitLen 128	72.145 ns/op	66.997 ns/op	1.08
intersect array and set length 128	2.2781 us/op	2.1784 us/op	1.05
Buffer.concat 32 items	1.9030 ns/op	2.1060 ns/op	0.90
pass gossip attestations to forkchoice per slot	2.9805 ms/op	3.5148 ms/op	0.85
computeDeltas	3.4811 ms/op	4.1671 ms/op	0.84
computeProposerBoostScoreFromBalances	908.08 us/op	843.08 us/op	1.08
altair processAttestation - 250000 vs - 7PWei normalcase	4.5076 ms/op	4.5696 ms/op	0.99
altair processAttestation - 250000 vs - 7PWei worstcase	6.4809 ms/op	6.7974 ms/op	0.95
altair processAttestation - setStatus - 1/6 committees join	211.85 us/op	259.93 us/op	0.82
altair processAttestation - setStatus - 1/3 committees join	404.32 us/op	484.11 us/op	0.84
altair processAttestation - setStatus - 1/2 committees join	563.91 us/op	747.34 us/op	0.75
altair processAttestation - setStatus - 2/3 committees join	720.06 us/op	845.13 us/op	0.85
altair processAttestation - setStatus - 4/5 committees join	1.0175 ms/op	1.1639 ms/op	0.87
altair processAttestation - setStatus - 100% committees join	1.2012 ms/op	1.4362 ms/op	0.84
altair processBlock - 250000 vs - 7PWei normalcase	33.219 ms/op	33.667 ms/op	0.99
altair processBlock - 250000 vs - 7PWei normalcase hashState	40.868 ms/op	47.271 ms/op	0.86
altair processBlock - 250000 vs - 7PWei worstcase	90.705 ms/op	107.27 ms/op	0.85
altair processBlock - 250000 vs - 7PWei worstcase hashState	94.801 ms/op	137.55 ms/op	0.69
phase0 processBlock - 250000 vs - 7PWei normalcase	4.1403 ms/op	4.0910 ms/op	1.01
phase0 processBlock - 250000 vs - 7PWei worstcase	47.439 ms/op	63.603 ms/op	0.75
altair processEth1Data - 250000 vs - 7PWei normalcase	1.5030 ms/op	1.6777 ms/op	0.90
Tree 40 250000 create	840.73 ms/op	906.10 ms/op	0.93
Tree 40 250000 get(125000)	287.92 ns/op	323.71 ns/op	0.89
Tree 40 250000 set(125000)	2.2913 us/op	2.7891 us/op	0.82
Tree 40 250000 toArray()	34.253 ms/op	35.241 ms/op	0.97
Tree 40 250000 iterate all - toArray() + loop	34.588 ms/op	35.713 ms/op	0.97
Tree 40 250000 iterate all - get(i)	113.00 ms/op	141.43 ms/op	0.80
MutableVector 250000 create	22.705 ms/op	28.254 ms/op	0.80
MutableVector 250000 get(125000)	13.306 ns/op	14.856 ns/op	0.90
MutableVector 250000 set(125000)	626.32 ns/op	665.90 ns/op	0.94
MutableVector 250000 toArray()	7.1992 ms/op	6.4591 ms/op	1.11
MutableVector 250000 iterate all - toArray() + loop	7.3098 ms/op	6.2435 ms/op	1.17
MutableVector 250000 iterate all - get(i)	3.6389 ms/op	3.3053 ms/op	1.10
Array 250000 create	6.4597 ms/op	5.9278 ms/op	1.09
Array 250000 clone - spread	2.5930 ms/op	2.5752 ms/op	1.01
Array 250000 get(125000)	1.1180 ns/op	1.1180 ns/op	1.00
Array 250000 set(125000)	1.1120 ns/op	1.1820 ns/op	0.94
Array 250000 iterate all - loop	167.87 us/op	134.59 us/op	1.25
effectiveBalanceIncrements clone Uint8Array 300000	91.605 us/op	88.708 us/op	1.03
effectiveBalanceIncrements clone MutableVector 300000	716.00 ns/op	763.00 ns/op	0.94
effectiveBalanceIncrements rw all Uint8Array 300000	254.17 us/op	279.53 us/op	0.91
effectiveBalanceIncrements rw all MutableVector 300000	172.35 ms/op	196.14 ms/op	0.88
phase0 afterProcessEpoch - 250000 vs - 7PWei	199.16 ms/op	205.63 ms/op	0.97
phase0 beforeProcessEpoch - 250000 vs - 7PWei	148.42 ms/op	153.05 ms/op	0.97
altair processEpoch - mainnet_e81889	721.74 ms/op	772.34 ms/op	0.93
mainnet_e81889 - altair beforeProcessEpoch	211.00 ms/op	215.34 ms/op	0.98
mainnet_e81889 - altair processJustificationAndFinalization	23.205 us/op	71.825 us/op	0.32
mainnet_e81889 - altair processInactivityUpdates	10.676 ms/op	11.927 ms/op	0.90
mainnet_e81889 - altair processRewardsAndPenalties	191.42 ms/op	204.54 ms/op	0.94
mainnet_e81889 - altair processRegistryUpdates	4.4820 us/op	14.676 us/op	0.31
mainnet_e81889 - altair processSlashings	1.0530 us/op	3.7790 us/op	0.28
mainnet_e81889 - altair processEth1DataReset	912.00 ns/op	4.2520 us/op	0.21
mainnet_e81889 - altair processEffectiveBalanceUpdates	3.4274 ms/op	2.7424 ms/op	1.25
mainnet_e81889 - altair processSlashingsReset	6.2390 us/op	33.699 us/op	0.19
mainnet_e81889 - altair processRandaoMixesReset	6.2270 us/op	29.162 us/op	0.21
mainnet_e81889 - altair processHistoricalRootsUpdate	1.0250 us/op	5.0800 us/op	0.20
mainnet_e81889 - altair processParticipationFlagUpdates	3.4630 us/op	17.300 us/op	0.20
mainnet_e81889 - altair processSyncCommitteeUpdates	872.00 ns/op	4.5930 us/op	0.19
mainnet_e81889 - altair afterProcessEpoch	186.49 ms/op	196.75 ms/op	0.95
phase0 processEpoch - mainnet_e58758	694.50 ms/op	770.65 ms/op	0.90
mainnet_e58758 - phase0 beforeProcessEpoch	288.21 ms/op	336.91 ms/op	0.86
mainnet_e58758 - phase0 processJustificationAndFinalization	23.613 us/op	65.100 us/op	0.36
mainnet_e58758 - phase0 processRewardsAndPenalties	155.31 ms/op	167.14 ms/op	0.93
mainnet_e58758 - phase0 processRegistryUpdates	12.080 us/op	36.669 us/op	0.33
mainnet_e58758 - phase0 processSlashings	871.00 ns/op	3.9490 us/op	0.22
mainnet_e58758 - phase0 processEth1DataReset	1.1030 us/op	3.5910 us/op	0.31
mainnet_e58758 - phase0 processEffectiveBalanceUpdates	1.8660 ms/op	2.4801 ms/op	0.75
mainnet_e58758 - phase0 processSlashingsReset	5.6860 us/op	15.792 us/op	0.36
mainnet_e58758 - phase0 processRandaoMixesReset	7.5870 us/op	23.302 us/op	0.33
mainnet_e58758 - phase0 processHistoricalRootsUpdate	1.0800 us/op	4.1010 us/op	0.26
mainnet_e58758 - phase0 processParticipationRecordUpdates	5.3670 us/op	23.517 us/op	0.23
mainnet_e58758 - phase0 afterProcessEpoch	151.51 ms/op	171.25 ms/op	0.88
phase0 processEffectiveBalanceUpdates - 250000 normalcase	2.6022 ms/op	2.5467 ms/op	1.02
phase0 processEffectiveBalanceUpdates - 250000 worstcase 0.5	3.0392 ms/op	3.1456 ms/op	0.97
altair processInactivityUpdates - 250000 normalcase	66.679 ms/op	77.124 ms/op	0.86
altair processInactivityUpdates - 250000 worstcase	65.999 ms/op	71.929 ms/op	0.92
phase0 processRegistryUpdates - 250000 normalcase	9.0300 us/op	34.994 us/op	0.26
phase0 processRegistryUpdates - 250000 badcase_full_deposits	432.43 us/op	492.35 us/op	0.88
phase0 processRegistryUpdates - 250000 worstcase 0.5	281.50 ms/op	301.34 ms/op	0.93
altair processRewardsAndPenalties - 250000 normalcase	158.55 ms/op	175.54 ms/op	0.90
altair processRewardsAndPenalties - 250000 worstcase	162.67 ms/op	171.64 ms/op	0.95
phase0 getAttestationDeltas - 250000 normalcase	13.461 ms/op	12.754 ms/op	1.06
phase0 getAttestationDeltas - 250000 worstcase	13.432 ms/op	14.376 ms/op	0.93
phase0 processSlashings - 250000 worstcase	6.1890 ms/op	6.4962 ms/op	0.95
altair processSyncCommitteeUpdates - 250000	279.28 ms/op	328.10 ms/op	0.85
BeaconState.hashTreeRoot - No change	463.00 ns/op	576.00 ns/op	0.80
BeaconState.hashTreeRoot - 1 full validator	61.451 us/op	73.681 us/op	0.83
BeaconState.hashTreeRoot - 32 full validator	703.48 us/op	830.66 us/op	0.85
BeaconState.hashTreeRoot - 512 full validator	7.6614 ms/op	12.295 ms/op	0.62
BeaconState.hashTreeRoot - 1 validator.effectiveBalance	78.515 us/op	108.91 us/op	0.72
BeaconState.hashTreeRoot - 32 validator.effectiveBalance	1.3151 ms/op	1.5353 ms/op	0.86
BeaconState.hashTreeRoot - 512 validator.effectiveBalance	18.185 ms/op	19.724 ms/op	0.92
BeaconState.hashTreeRoot - 1 balances	56.386 us/op	74.699 us/op	0.75
BeaconState.hashTreeRoot - 32 balances	623.27 us/op	802.65 us/op	0.78
BeaconState.hashTreeRoot - 512 balances	6.1374 ms/op	7.5099 ms/op	0.82
BeaconState.hashTreeRoot - 250000 balances	101.12 ms/op	111.21 ms/op	0.91
aggregationBits - 2048 els - zipIndexesInBitList	29.153 us/op	27.226 us/op	1.07
regular array get 100000 times	67.435 us/op	52.717 us/op	1.28
wrappedArray get 100000 times	67.439 us/op	53.800 us/op	1.25
arrayWithProxy get 100000 times	29.580 ms/op	37.607 ms/op	0.79
ssz.Root.equals	568.00 ns/op	642.00 ns/op	0.88
byteArrayEquals	479.00 ns/op	547.00 ns/op	0.88
shuffle list - 16384 els	11.249 ms/op	11.888 ms/op	0.95
shuffle list - 250000 els	166.00 ms/op	173.51 ms/op	0.96
processSlot - 1 slots	12.820 us/op	16.497 us/op	0.78
processSlot - 32 slots	1.9300 ms/op	2.2653 ms/op	0.85
getEffectiveBalanceIncrementsZeroInactive - 250000 vs - 7PWei	340.71 us/op	611.64 us/op	0.56
getCommitteeAssignments - req 1 vs - 250000 vc	5.2819 ms/op	5.6983 ms/op	0.93
getCommitteeAssignments - req 100 vs - 250000 vc	7.3399 ms/op	8.1420 ms/op	0.90
getCommitteeAssignments - req 1000 vs - 250000 vc	7.8458 ms/op	8.3962 ms/op	0.93
RootCache.getBlockRootAtSlot - 250000 vs - 7PWei	10.950 ns/op	9.4100 ns/op	1.16
state getBlockRootAtSlot - 250000 vs - 7PWei	1.2282 us/op	1.0608 us/op	1.16
computeProposers - vc 250000	16.617 ms/op	17.940 ms/op	0.93
computeEpochShuffling - vc 250000	178.38 ms/op	170.00 ms/op	1.05
getNextSyncCommittee - vc 250000	280.27 ms/op	298.55 ms/op	0.94

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