Common: Genesis state logic improved

[cbrzn]

This is a very WIP PR that aims to improve the genesis state management in the common library. Open to any feedback just wanted to see what you think

• State root and hash of genesis block can be passed as GenesisState in attribute customChains
• Now we show genesis block hash and state root in client process logs
• Genesis state is now storing storage, nonce, code and balance attributes to work with complex genesis files

Ideas on TODO:

• Handle geth genesis file format in common
• Add some examples
• Study if we can remove the static files in genesisState() method and try to retrieve it from configuration given, this way we can remove a lot of code from Common package

[codecov]

Codecov Report

Merging #1755 (1cecab7) into master (c842a97) will increase coverage by 1.04%.
The diff coverage is 70.00%.

Flag	Coverage Δ
block	85.57% <ø> (ø)
blockchain	83.28% <ø> (ø)
client	?
common	42.53% <70.00%> (-51.38%)	⬇️
devp2p	82.36% <ø> (-0.14%)	⬇️
ethash	90.76% <ø> (ø)
trie	86.18% <ø> (ø)
tx	89.94% <ø> (ø)
util	92.62% <ø> (ø)
vm	81.19% <ø> (ø)

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[holgerd77]

This is tackling too many things at once (as written per DM), will close this. Please re-submit separately (first: tests for existing functionality, second: geth genesis inclusion).