Implement RETURNDATALOAD (EOF)

[pdobacz]

Closes #775

Inclusion is still somewhat pending, but this is likely to be included in the EOF instruction set to avoid code size regressions reported by compiler teams.

For this reason, I'm opening as draft, but this is reviewable. Does including a new opcode require any additional work?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (951b88d) 97.91% compared to head (5f61632) 97.94%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #786      +/-   ##
==========================================
+ Coverage   97.91%   97.94%   +0.02%     
==========================================
  Files         110      110              
  Lines       10670    10791     +121     
==========================================
+ Hits        10448    10569     +121     
  Misses        222      222              

Flag	Coverage Δ
blockchaintests	59.88% <0.00%> (-0.49%)	⬇️
statetests	62.14% <0.00%> (-0.22%)	⬇️
statetests-silkpre	25.57% <5.98%> (-0.25%)	⬇️
unittests	95.94% <100.00%> (+0.04%)	⬆️

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Files	Coverage Δ
lib/evmone/advanced_instructions.cpp	100.00% <ø> (ø)
lib/evmone/baseline_instruction_table.cpp	100.00% <ø> (ø)
lib/evmone/instructions.hpp	100.00% <100.00%> (ø)
test/unittests/evm_calls_test.cpp	100.00% <100.00%> (ø)
test/unittests/instructions_test.cpp	89.58% <ø> (ø)
test/utils/bytecode.hpp	96.01% <100.00%> (+0.03%)	⬆️