Test case: initcode-mode not being EOF-validated

[pdobacz]

Recently on the EOF impl call we discussed a potential rule to validate and prohibit "weird" mixing of initcode-mode being on or off - during EOF validation.

We concluded we do not find such validation rule useful enough. In case this rule withstands the test of time, we should have a test case for this.

I think this is a test case where we acertain, that none of the following conditions are validated:

• Each EOF subcontainer must either be referenced by an EOFCREATE or a RETURNCONTRACT instruction, but never both
• Each EOF subcontainer may either contain RETURNCONTRACT or RETURN / STOP instructions, but never a mix of these two kinds
• A subcontainer referenced by an EOFCREATE must never contain a RETURN / STOP instruction, whereas a subcontainer referenced by a RETURNCONTRACT must never contain a RETURNCONTRACT

This quote is taken from the potential addition to the rationale section of EIP-7620, as PRed here: https://github.com/ethereum/EIPs/blob/d8149857a036b69f24c9f8d56fa87dbd0bbf2d0c/EIPS/eip-7620.md#eof-validation-checking-initcode-mode

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.32%. Comparing base (44a029d) to head (94cf08e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #855   +/-   ##
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  Coverage   98.32%   98.32%           
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  Files         129      129           
  Lines       15515    15525   +10     
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+ Hits        15255    15265   +10     
  Misses        260      260           

Flag	Coverage Δ
statetests	27.78% <0.00%> (-0.03%)	⬇️
statetests-silkpre	18.81% <0.00%> (-0.02%)	⬇️
unittests	94.12% <100.00%> (+<0.01%)	⬆️

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Files	Coverage Δ
test/unittests/eof_validation_test.cpp	100.00% <100.00%> (ø)

[gumb0]

Please rebase.