Add fuzz tests for parsing and kernel generation

[drhagen]

The generate test hangs or fails for reasons to be investigated later.

[codecov-commenter]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (36d434c) 89.05% compared to head (b1e0068) 89.02%.

Files	Patch %	Lines
src/tensora/expression/ast.py	63.63%	2 Missing and 2 partials ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master      #41      +/-   ##
==========================================
- Coverage   89.05%   89.02%   -0.04%     
==========================================
  Files          54       54              
  Lines        2943     2951       +8     
  Branches      524      526       +2     
==========================================
+ Hits         2621     2627       +6     
  Misses        248      248              
- Partials       74       76       +2     

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