Rename Felt to Felt252

[Oppen]

To match https://github.com/starkware-libs/cairo/pull/2479/files

[codecov]

Codecov Report

Merging #899 (e76e2fe) into main (6790b25) will increase coverage by 97.38%.
The diff coverage is 98.28%.

@@            Coverage Diff            @@
##           main     #899       +/-   ##
=========================================
+ Coverage      0   97.38%   +97.38%     
=========================================
  Files         0       69       +69     
  Lines         0    29217    +29217     
=========================================
+ Hits          0    28454    +28454     
- Misses        0      763      +763     

Impacted Files	Coverage Δ
src/hint_processor/hint_processor_definition.rs	100.00% <ø> (ø)
src/serde/deserialize_utils.rs	96.44% <71.42%> (ø)
...int_processor/builtin_hint_processor/math_utils.rs	97.75% <87.67%> (ø)
src/serde/deserialize_program.rs	97.86% <88.88%> (ø)
...uiltin_hint_processor/cairo_keccak/keccak_hints.rs	93.91% <89.47%> (ø)
src/vm/vm_memory/memory.rs	98.88% <97.22%> (ø)
src/types/relocatable.rs	99.67% <98.59%> (ø)
felt/src/lib.rs	89.43% <98.98%> (ø)
src/cairo_run.rs	98.52% <100.00%> (ø)
..._processor/builtin_hint_processor/blake2s_utils.rs	99.74% <100.00%> (ø)
... and 36 more

... and 23 files with indirect coverage changes

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[fmoletta]

LGTM