fuzz roundtrip tests and reasonable initial fixed rate and timestretch

[jrhea]

• Added fuzzing to roundtrip tests
• Establish sane bounds for initial fixed rate and time stretch. tl;dr is:

initialFixedRate = [ 0.1%, 50% ]

lower = max(initialFixedRate/2, 0.5%)
upper = 2 x max(lower, initialFixedRate) 
initialTimeStretchFixedRate = [ lower, upper ]

[github-actions]

Hyperdrive Gas Benchmark

Benchmark suite	Current: 37dea61	Previous: 78dee14	Deviation	Status
addLiquidity: min	1633 gas	1633 gas	0%	🟰
addLiquidity: avg	67489 gas	65418 gas	3.1658%	🚨
addLiquidity: max	292045 gas	292045 gas	0%	🟰
checkpoint: min	1150 gas	1150 gas	0%	🟰
checkpoint: avg	48569 gas	48538 gas	0.0639%	🚨
checkpoint: max	191003 gas	191003 gas	0%	🟰
closeLong: min	1558 gas	1558 gas	0%	🟰
closeLong: avg	28063 gas	28103 gas	-0.1423%	✅
closeLong: max	149207 gas	151196 gas	-1.3155%	✅
closeShort: min	1549 gas	1549 gas	0%	🟰
closeShort: avg	29847 gas	29854 gas	-0.0234%	✅
closeShort: max	125618 gas	145678 gas	-13.7701%	✅
initialize: min	1582 gas	1582 gas	0%	🟰
initialize: avg	213296 gas	213322 gas	-0.0122%	✅
initialize: max	255137 gas	255137 gas	0%	🟰
openLong: min	1487 gas	1487 gas	0%	🟰
openLong: avg	50501 gas	50410 gas	0.1805%	🚨
openLong: max	184891 gas	184891 gas	0%	🟰
openShort: min	1608 gas	1608 gas	0%	🟰
openShort: avg	50084 gas	50078 gas	0.0120%	🚨
openShort: max	180398 gas	180398 gas	0%	🟰
redeemWithdrawalShares: min	1575 gas	1575 gas	0%	🟰
redeemWithdrawalShares: avg	20189 gas	19265 gas	4.7963%	🚨
redeemWithdrawalShares: max	57811 gas	57811 gas	0%	🟰
removeLiquidity: min	1639 gas	1639 gas	0%	🟰
removeLiquidity: avg	148272 gas	149669 gas	-0.9334%	✅
removeLiquidity: max	324287 gas	324379 gas	-0.0284%	✅

This comment was automatically generated by workflow using github-action-benchmark.

[coveralls]

coverage: 95.552%. remained the same
when pulling 233755e on test-fix
into 78dee14 on main.

[jalextowle]

LGTM, just a few nits.