genesis: add GenesisAccountData type for use in GenesisAllocation

[cce]

Summary

Alternate for #5447 that specifies the narrow set of fields allowed in the GenesisAllocation (the "alloc" part of the genesis.json file).

#5316

Test Plan

Existing tests updated, should pass

[codecov]

Codecov Report

Merging #5463 (92ac71f) into master (fd60def) will decrease coverage by 0.02%.
The diff coverage is 93.75%.

@@            Coverage Diff             @@
##           master    #5463      +/-   ##
==========================================
- Coverage   55.57%   55.56%   -0.02%     
==========================================
  Files         447      447              
  Lines       63356    63366      +10     
==========================================
- Hits        35213    35209       -4     
- Misses      25772    25780       +8     
- Partials     2371     2377       +6     

Impacted Files	Coverage Δ
netdeploy/remote/deployedNetwork.go	18.58% <0.00%> (ø)
data/bookkeeping/genesis.go	35.36% <100.00%> (+8.97%)	⬆️
gen/generate.go	66.66% <100.00%> (ø)

... and 10 files with indirect coverage changes

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[algochoi]

I think this looks good - I'm also slowly in favor of a less intrusive and isolated change in favor of #5447, especially since data in the genesis file should rarely change.