Several evaluator and prover parallelizations

[gabrielbosio]

Also, I've made the verifier benchmarks consistent with the proofs they use.
This PR improves the performance of the prover by 5%.

[MauroToscano]

I have also fixed the cfg features that were broken

[codecov-commenter]

Codecov Report

Merging #196 (6d50bfa) into main (3002245) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #196      +/-   ##
==========================================
+ Coverage   94.39%   94.43%   +0.04%     
==========================================
  Files          33       33              
  Lines        6418     6472      +54     
==========================================
+ Hits         6058     6112      +54     
  Misses        360      360              

Files Changed	Coverage Δ
stark_prover/src/constraints/evaluator.rs	93.43% <100.00%> (+0.14%)	⬆️
stark_prover/src/prover.rs	99.86% <100.00%> (+<0.01%)	⬆️

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