ChainID support in testeth

[gumb0]

With this fix testeth passes ChainID tests from ethereum/tests#627

The simple fix is to always use the same ChainID from the mainnet config, assuming all network configs use only this ChainID.

Note: VM tests still always return 0 ChainID, I didn't bother to fix it as VM tests are not maintained anyway.

aleth/test/tools/jsontests/vm.cpp

Line 113 in 1e25be8

return {blockHeader, _lastBlockHashes, 0, 0};

aleth/test/tools/jsontests/vm.cpp

Line 446 in 1e25be8

dev::test::FakeExtVM test(eth::EnvInfo{BlockHeader{}, lastBlockHashes, 0, 0});

[codecov-io]

Codecov Report

Merging #5727 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #5727      +/-   ##
==========================================
+ Coverage    63.2%   63.23%   +0.02%     
==========================================
  Files         353      353              
  Lines       30271    30274       +3     
  Branches     3390     3390              
==========================================
+ Hits        19134    19144      +10     
+ Misses       9904     9894      -10     
- Partials     1233     1236       +3