Tests: Add test defending against regression in testnet genesis generation

[michaeldiamant]

Attempts to address the following question from #4643 (review):

Can we somehow check if this generates the genesis for testnet as well?

Adds a test confirming gen/testnet.json matches installer/genesis/testnet/genesis.json excluding blotted out fields.

[codecov]

Codecov Report

Merging #4741 (c22866f) into master (fa77937) will decrease coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4741      +/-   ##
==========================================
- Coverage   54.62%   54.55%   -0.07%     
==========================================
  Files         414      414              
  Lines       53514    53514              
==========================================
- Hits        29231    29197      -34     
- Misses      21860    21887      +27     
- Partials     2423     2430       +7     

Impacted Files	Coverage Δ
ledger/roundlru.go	90.56% <0.00%> (-5.67%)	⬇️
ledger/blockqueue.go	85.63% <0.00%> (-2.88%)	⬇️
crypto/merkletrie/trie.go	66.42% <0.00%> (-2.19%)	⬇️
agreement/cryptoVerifier.go	67.60% <0.00%> (-2.12%)	⬇️
agreement/proposalManager.go	96.07% <0.00%> (-1.97%)	⬇️
network/wsPeer.go	66.50% <0.00%> (-1.95%)	⬇️
crypto/merkletrie/node.go	91.62% <0.00%> (-1.87%)	⬇️
network/wsNetwork.go	65.34% <0.00%> (-0.37%)	⬇️
ledger/acctupdates.go	69.05% <0.00%> (-0.25%)	⬇️
catchup/service.go	68.88% <0.00%> (ø)

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[algorandskiy]

Thanks, Michael for the auto test. I honestly thought about one time manual test as a safety measure for that particular PR.