Check in code used to generate plots for loop_tool in paper

[bwasti]

as in title, this adds the code used to sweep through loop_tool parameters using CompilerGym

[ChrisCummins]

Code looks good, thanks @bwasti! Could you add the MIT license header to these new files, and a short description of what they do?

[ChrisCummins]

Flagging here that its safe to ignore the CI signals which are currently all broken pending #453

[codecov-commenter]

Codecov Report

Merging #457 (5bc2efa) into development (94c9e79) will decrease coverage by 0.03%.
The diff coverage is n/a.

❗ Current head 5bc2efa differs from pull request most recent head 10f52f6. Consider uploading reports for the commit 10f52f6 to get more accurate results

@@               Coverage Diff               @@
##           development     #457      +/-   ##
===============================================
- Coverage        85.64%   85.61%   -0.04%     
===============================================
  Files              111      111              
  Lines             6181     6181              
===============================================
- Hits              5294     5292       -2     
- Misses             887      889       +2     

Impacted Files	Coverage Δ
compiler_gym/envs/llvm/datasets/cbench.py	76.69% <0.00%> (-0.76%)	⬇️

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[ChrisCummins]

Licenses added, merging.