rest api: Allow fast track transaction broadcasting via txHandler

[algorandskiy]

Summary

Added a new RawTransactionsAsync handler (enabled with ExperimentalAPI) that shortcuts to non-blocking txHandler call. This is useful for local pingpong high TPS testing. (Although real high TPS is still blocked by Echo's logging middleware, but this is a separate topic).

This handler is used in pingpong via libgoal.
Also set EnableExperimentalAPI=true for local network templates and scenario1s.

Test Plan

Tested locally with pingpong, 2.5 TPS observed out of 3k requested - here are the data for 2m run:

pingpong run -d ~/networks/two-fut/Primary --tps 3000 --numaccounts 50 --refresh 3700 --async --quiet --run 120
...
16550 sent, 3306.68/s (16550 total) (16600 sc 15112 sts)
13950 sent, 2731.90/s (30500 total) (30550 sc 30432 sts)
16150 sent, 3298.26/s (46650 total) (46700 sc 45121 sts)
14150 sent, 2755.04/s (60800 total) (60850 sc 60529 sts)
16250 sent, 3340.10/s (77050 total) (77100 sc 75125 sts)
13950 sent, 2760.98/s (91000 total) (91050 sc 90219 sts)

[winder]

Could this be a new endpoint that isn't exposed to the public API / SDKs? I believe tagging it "experimental" will opt it out of the downstream code generation.

Fixed as requested

[winder]

Thanks for the change. LGTM.

[codecov]

Codecov Report

Merging #5535 (ad3c8d7) into master (5acab71) will decrease coverage by 0.01%.
Report is 1 commits behind head on master.
The diff coverage is 12.19%.

@@            Coverage Diff             @@
##           master    #5535      +/-   ##
==========================================
- Coverage   54.94%   54.93%   -0.01%     
==========================================
  Files         463      463              
  Lines       64476    64515      +39     
==========================================
+ Hits        35427    35444      +17     
- Misses      26668    26692      +24     
+ Partials     2381     2379       -2     

Files Changed	Coverage Δ
daemon/algod/api/server/v2/handlers.go	0.81% <0.00%> (-0.01%)	⬇️
data/txHandler.go	71.73% <0.00%> (-1.40%)	⬇️
libgoal/transactions.go	0.00% <0.00%> (ø)
netdeploy/networkTemplate.go	42.85% <0.00%> (-0.27%)	⬇️
node/follower_node.go	34.10% <0.00%> (+1.54%)	⬆️
node/node.go	4.14% <0.00%> (-0.02%)	⬇️
shared/pingpong/config.go	0.00% <ø> (ø)
shared/pingpong/pingpong.go	0.00% <0.00%> (ø)
daemon/algod/api/server/v2/test/helpers.go	77.04% <100.00%> (+0.47%)	⬆️

... and 7 files with indirect coverage changes

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[algorandskiy]

merged master and regenerated routes

[AlgoAxel]

See cce's comment about the function naming being somewhat confusing, but this appears to be the same as when I previously approved.

[algorandskiy]

rebased master