CI: use GHA for codegen_verification

[cce]

This moves the codegen_verification task to Github Actions, as it is similar to the other types of static checks and linting jobs already in GHA.

[codecov]

Codecov Report

Merging #4412 (52f02f5) into master (fd488f8) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4412      +/-   ##
==========================================
- Coverage   55.34%   55.32%   -0.02%     
==========================================
  Files         400      400              
  Lines       50797    50797              
==========================================
- Hits        28112    28104       -8     
- Misses      20311    20315       +4     
- Partials     2374     2378       +4     

Impacted Files	Coverage Δ
ledger/roundlru.go	90.56% <0.00%> (-5.67%)	⬇️
ledger/blockqueue.go	84.48% <0.00%> (-2.88%)	⬇️
crypto/merkletrie/trie.go	66.42% <0.00%> (-2.19%)	⬇️
crypto/merkletrie/node.go	91.62% <0.00%> (-1.87%)	⬇️
data/abi/abi_type.go	87.67% <0.00%> (-0.95%)	⬇️
ledger/tracker.go	73.93% <0.00%> (-0.86%)	⬇️
network/wsNetwork.go	64.70% <0.00%> (-0.20%)	⬇️
network/wsPeer.go	67.67% <0.00%> (ø)
ledger/acctonline.go	79.00% <0.00%> (+0.52%)	⬆️
ledger/acctupdates.go	70.52% <0.00%> (+0.60%)	⬆️
... and 3 more

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[cce]

manually compared the Github Actions output and the CircleCI output for codegen_verification on the same build and they look the same to me.

[winder]

Looks pretty straightforward.