tracing: Separate gas parameter

[chfast]

Decouple "gas left" from ExecutionState and pass it as separate param.

[codecov]

Codecov Report

Merging #599 (abec11f) into master (7e4c268) will not change coverage.
The diff coverage is 100.00%.

❗ Current head abec11f differs from pull request most recent head 477dd5b. Consider uploading reports for the commit 477dd5b to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #599   +/-   ##
=======================================
  Coverage   97.11%   97.11%           
=======================================
  Files          74       74           
  Lines        7445     7445           
=======================================
  Hits         7230     7230           
  Misses        215      215           

Flag	Coverage Δ
blockchaintests	63.61% <0.00%> (ø)
statetests	63.09% <0.00%> (ø)
unittests	93.95% <100.00%> (ø)

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

Impacted Files	Coverage Δ
test/unittests/tracing_test.cpp	100.00% <ø> (ø)
lib/evmone/baseline.cpp	100.00% <100.00%> (ø)
lib/evmone/tracing.cpp	100.00% <100.00%> (ø)
lib/evmone/tracing.hpp	94.11% <100.00%> (ø)

... and 2 files with indirect coverage changes

[axic]

What is the motivation?

[chfast]

We are going to remove gas_left from ExecutionState in next PR.

[chfast]

See continuation in #600.

[rodiazet]

state.gas_left is used also in a couple of different places in the code. Are you going to separate it in additional PRs?

[chfast]

See continuation in #600.