EOF validation tests runner: support initcode flag

[gumb0]

This is the fixture format agreed on EOF implementers call and produced by EEST in ethereum/execution-spec-tests#651

Based on #916 because it removes the tests for initcode_runtime container kind, and those were failing the run of exported validation tests.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.23%. Comparing base (f3222be) to head (9340a9c).

❗ Current head 9340a9c differs from pull request most recent head aa63844

Please upload reports for the commit aa63844 to get more accurate results.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #936       +/-   ##
===========================================
+ Coverage   22.84%   94.23%   +71.39%     
===========================================
  Files         139      142        +3     
  Lines       16078    16120       +42     
===========================================
+ Hits         3673    15191    +11518     
+ Misses      12405      929    -11476     

Flag	Coverage Δ
eof_execution_spec_tests	16.51% <25.00%> (+0.01%)	⬆️
ethereum_tests_silkpre	18.85% <0.00%> (?)
execution_spec_tests	17.98% <0.00%> (+0.01%)	⬆️
unittests	89.67% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
test/eoftest/eoftest_runner.cpp	87.50% <100.00%> (+12.50%)	⬆️
test/unittests/eof_validation.cpp	92.98% <100.00%> (+92.98%)	⬆️

... and 119 files with indirect coverage changes