Check for overflows in relocatable operations

[fmoletta]

This PR does the following:

• Add checks for possible overflows when adding to a relocatable's offset (which can panic if the addition exceeds usize::MAX)
• Move Relocatable operations to trait implementations

Depends on #855

[codecov]

Codecov Report

Merging #859 (d0e12f3) into math-error (4beb4c8) will increase coverage by 0.00%.
The diff coverage is 97.76%.

@@             Coverage Diff             @@
##           math-error     #859   +/-   ##
===========================================
  Coverage       96.90%   96.91%           
===========================================
  Files              69       69           
  Lines           29006    28965   -41     
===========================================
- Hits            28108    28070   -38     
+ Misses            898      895    -3     

Impacted Files	Coverage Δ
src/hint_processor/hint_processor_utils.rs	88.88% <80.00%> (ø)
src/vm/vm_core.rs	97.48% <90.00%> (-0.04%)	⬇️
src/types/relocatable.rs	99.66% <98.73%> (+0.63%)	⬆️
..._processor/builtin_hint_processor/blake2s_utils.rs	99.74% <100.00%> (-0.01%)	⬇️
...uiltin_hint_processor/cairo_keccak/keccak_hints.rs	93.96% <100.00%> (ø)
...rocessor/builtin_hint_processor/dict_hint_utils.rs	99.22% <100.00%> (-0.01%)	⬇️
...cessor/builtin_hint_processor/find_element_hint.rs	96.46% <100.00%> (ø)
...t_processor/builtin_hint_processor/keccak_utils.rs	100.00% <100.00%> (ø)
...int_processor/builtin_hint_processor/math_utils.rs	97.94% <100.00%> (ø)
...hint_processor/builtin_hint_processor/pow_utils.rs	100.00% <100.00%> (ø)
... and 25 more

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[Oppen]

Typical (equivalent) signature:

Suggested change

	type Output = Result<Relocatable, MathError>;
	fn add(self, other: &MaybeRelocatable) -> Result<Relocatable, MathError> {
	type Output = Result<Relocatable, MathError>;
	fn add(self, other: &MaybeRelocatable) -> Self::Output {

I'm not 100% sure returning a Result<_> from an operator is what anybody would expect, as typically they'd use checked_* to handle errors and let it panic! otherwise. Still, this is infinitely better than what we had, so I'm OK with it.

[Jrigada]

Much nicer