feat: improve ContractClass parsing

[MegaRedHand]

Closes #768

Description

This PR makes the changes mentioned in #768 in ContractClass parsing, moving the functionality away from TryFrom implementations. Among other things, this let's us use generics for Paths and Readers.

Checklist

• Linked to Github Issue
• Unit tests added
• Integration tests added.
• This change requires new documentation.
  • Documentation has been added/updated.

[codecov-commenter]

Codecov Report

Merging #779 (439202e) into main (29dd9e8) will decrease coverage by 0.05%.
The diff coverage is 92.47%.

@@            Coverage Diff             @@
##             main     #779      +/-   ##
==========================================
- Coverage   92.51%   92.47%   -0.05%     
==========================================
  Files          51       51              
  Lines       12090    12049      -41     
==========================================
- Hits        11185    11142      -43     
- Misses        905      907       +2     

Impacted Files	Coverage Δ
src/testing/erc20.rs	100.00% <ø> (ø)
.../api/contract_classes/deprecated_contract_class.rs	86.59% <66.66%> (-1.06%)	⬇️
...re/contract_address/deprecated_contract_address.rs	93.71% <100.00%> (-0.04%)	⬇️
src/lib.rs	98.70% <100.00%> (-0.01%)	⬇️
src/state/cached_state.rs	93.34% <100.00%> (-0.02%)	⬇️
src/state/in_memory_state_reader.rs	90.69% <100.00%> (-0.08%)	⬇️
src/state/state_cache.rs	95.59% <100.00%> (-0.03%)	⬇️
src/syscalls/deprecated_syscall_handler.rs	98.37% <100.00%> (-0.01%)	⬇️
src/testing/mod.rs	100.00% <100.00%> (ø)
src/testing/state.rs	96.97% <100.00%> (-0.03%)	⬇️
... and 5 more