Parallelize radix-2 arbitrary size kernel

[Shnatsel]

Same as #104 but applied to radix-2 kernel, to enable direct comparison

[codecov-commenter]

Codecov Report

❌ Patch coverage is 96.72131% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.50%. Comparing base (3aa61ad) to head (2eda8dd).

Files with missing lines	Patch %	Lines
src/algorithms/dit.rs	75.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #108      +/-   ##
==========================================
- Coverage   98.87%   94.50%   -4.38%     
==========================================
  Files          10       10              
  Lines        2227     2347     +120     
==========================================
+ Hits         2202     2218      +16     
- Misses         25      129     +104     

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[Shnatsel]

This is strictly inferior to #104 so closing in favor of #104