use our own is_prime impl

[tdelabro]

custom is_prime

Description

num-prime cannot be used in a no_std env.
This PR replace the calls to num_prime::is_prime with our custom impl

It incidentally restore no_std support for cairo-vm

[codecov]

Codecov Report

Merging #1238 (2b77816) into main (4221723) will increase coverage by 0.00%.
The diff coverage is 99.55%.

@@           Coverage Diff            @@
##             main    #1238    +/-   ##
========================================
  Coverage   97.61%   97.62%            
========================================
  Files          88       89     +1     
  Lines       36112    37001   +889     
========================================
+ Hits        35251    36122   +871     
- Misses        861      879    +18     

Impacted Files	Coverage Δ
vm/src/math_utils/is_prime.rs	99.55% <99.55%> (ø)
vm/src/math_utils/mod.rs	99.39% <100.00%> (ø)
vm/src/serde/deserialize_program.rs	96.75% <100.00%> (ø)

... and 3 files with indirect coverage changes

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[MegaRedHand]

Thanks for your help! 😄

[tdelabro]

By the way, do you have a way to check if this new way of checking for prime numbers does not hurt performances?

[MegaRedHand]

Yes! We have benchmarks that run as part of the CI. The numbers usually appear as a comment on the PR, but in this case, it fails because of permissions. You can see the raw output in the logs.

[tdelabro]

@MegaRedHand
base field_arithmetic_get_square_benchmark | 153.4 ± 5.7 | 148.9 | 168.5 | 1.00 |\n|`

± 5.7 is it bad?

[MegaRedHand]

It ran ~14% slower than main (you can see that here), but no-std is a priority. We already mitigated it by adding the original implementation as an std alternative in #1232. Also opened an issue to look for a better alternative: #1243.