Add Bench for Babybear

[jotabulacios]

Add Bench for Babybear

Description

This PR adds benchmarks for BabyBear field arithmetic operations in both the base field and its degree-4 extension field.

Results for 1 million operations

Operation	Lambdaworks	Plonky3	Speedup
Addition	610.68 µs	629.35 µs	2.97%
Multiplication	747.44 µs	701.59 µs	-6.53%
Squaring	1.0284 ms	612.02 µs	-68.03%
Division	138.03 ms	84.085 ms	-64.16%
Inversion	139.71 ms	80.817 ms	-72.87%
Addition Fp4	877.75 µs	529.44 µs	-65.79%
Multiplication Fp4	14.218 ms	12.625 ms	-12.62%
Squaring Fp4	10.603 ms	12.177 ms	12.93%
Division Fp4	168.18 ms	188.82 ms	10.93%
Inversion Fp4	193.61 ms	162.75 ms	-18.96%

Checklist

• Benchmarks added/run

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.14%. Comparing base (2ce8b2e) to head (90772ef).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #947   +/-   ##
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  Coverage   71.14%   71.14%           
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  Files         153      153           
  Lines       33129    33129           
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  Hits        23570    23570           
  Misses       9559     9559           

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