use Felt252 for chain ids

[SantiagoPittella]

Description

Change chain_id type to Felt252, allowing custom chains.

Closes #844

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 #847 (c4e227a) into main (3bbcf53) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #847      +/-   ##
==========================================
- Coverage   91.74%   91.73%   -0.02%     
==========================================
  Files          54       54              
  Lines       12842    12838       -4     
==========================================
- Hits        11782    11777       -5     
- Misses       1060     1061       +1     

Impacted Files	Coverage Δ
src/definitions/block_context.rs	98.33% <100.00%> (-1.67%)	⬇️
src/execution/mod.rs	97.57% <100.00%> (ø)
src/syscalls/business_logic_syscall_handler.rs	77.95% <100.00%> (ø)
...calls/deprecated_business_logic_syscall_handler.rs	90.69% <100.00%> (ø)
src/syscalls/deprecated_syscall_handler.rs	98.36% <100.00%> (-0.01%)	⬇️
src/testing/mod.rs	100.00% <100.00%> (ø)
src/testing/state.rs	94.01% <100.00%> (ø)