Refactor jit quantized tensor representation

[laggui]

Checklist

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

Related Issues/PRs

On the way to burn-fusion quantize

Follow-up to #2479

Changes

• Simplified quantized tensor handle repr (one handle per qtensor)
• Removed strategy from QTensorPrimitive trait
• Refactored burn-jit quantized tensor repr and kernel
  • Removed QJitTensor (use JitTensor with QFloat dtype)
  • Refactored cube kernels w/ stored quantization params in cube tensor and new

Testing

Unit tests

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 206 lines in your changes missing coverage. Please review.

Project coverage is 81.90%. Comparing base (ebd7649) to head (a93e8da).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...rates/burn-jit/src/kernel/quantization/quantize.rs	33.94%	72 Missing ⚠️
...tes/burn-jit/src/kernel/quantization/dequantize.rs	44.44%	45 Missing ⚠️
crates/burn-jit/src/kernel/quantization/qtensor.rs	4.34%	22 Missing ⚠️
crates/burn-tch/src/tensor.rs	0.00%	10 Missing ⚠️
crates/burn-fusion/src/server.rs	25.00%	9 Missing ⚠️
crates/burn-jit/src/tensor/base.rs	62.50%	9 Missing ⚠️
crates/burn-fusion/src/tensor.rs	75.86%	7 Missing ⚠️
crates/burn-fusion/src/client/mutex.rs	53.84%	6 Missing ⚠️
crates/burn-fusion/src/ops/qtensor.rs	77.27%	5 Missing ⚠️
crates/burn-ndarray/src/backend.rs	0.00%	5 Missing ⚠️
... and 8 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2604      +/-   ##
==========================================
+ Coverage   81.86%   81.90%   +0.04%     
==========================================
  Files         832      831       -1     
  Lines      106399   106121     -278     
==========================================
- Hits        87099    86920     -179     
+ Misses      19300    19201      -99     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.