refactor(pc): string -> [4]bytes

[itsdevbear]

• More performant
• Remove unsafe and reflect usage

[codecov]

Codecov Report

Merging #1059 (8ce4ce0) into main (a0dce68) will decrease coverage by 0.12%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1059      +/-   ##
==========================================
- Coverage   54.09%   53.97%   -0.12%     
==========================================
  Files         102      101       -1     
  Lines        5341     5328      -13     
==========================================
- Hits         2889     2876      -13     
  Misses       2279     2279              
  Partials      173      173              

Files Changed	Coverage Δ
eth/core/precompile/method.go	93.75% <ø> (ø)
eth/core/precompile/factories.go	86.04% <100.00%> (ø)
eth/core/precompile/method_validation.go	91.08% <100.00%> (-0.09%)	⬇️
eth/core/precompile/stateful_container.go	100.00% <100.00%> (ø)

[itsdevbear]

todo: write a quick test to make sure it's not using the pointer memory address as the key by accident

[itsdevbear]

good to merge