Add QTensorOps docs + refactor tests to simplify inputs

[laggui]

Checklist

• Confirmed that run-checks all script has been executed.

Changes

• Refactored qtensor ops tests w/ QTensor helper struct
  • Previously defined inputs was clunky, error prone and difficult to understand. Now anyone can more easily add tests for operations using floating point values. QTensor methods will automatically quantize the inputs.
• Added missing q_split tests
• Added QTensorOps docs to burn contrib book
• Fixed zero scale edge cases everywhere

[codecov]

Codecov Report

Attention: Patch coverage is 99.52229% with 3 lines in your changes missing coverage. Please review.

Project coverage is 82.31%. Comparing base (1e511b5) to head (47fb7e4).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
...es/burn-tensor/src/tests/quantization/ops/chunk.rs	76.92%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2557      +/-   ##
==========================================
- Coverage   82.50%   82.31%   -0.19%     
==========================================
  Files         828      831       +3     
  Lines      107040   105703    -1337     
==========================================
- Hits        88314    87013    -1301     
+ Misses      18726    18690      -36     

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[louisfd]

LGTM! Much cleaner :)