Replace return with terminate

[maxtremblay]

This is the counterpart of tracel-ai/cubecl#449.

The support for return was unintuitive, so I replace it with a terminate!() macro that terminates the execution of the current unit within the kernel.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 44 lines in your changes missing coverage. Please review.

Project coverage is 83.57%. Comparing base (7ddb5af) to head (c8825d1).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...rates/burn-jit/src/kernel/quantization/quantize.rs	0.00%	5 Missing ⚠️
crates/burn-jit/src/kernel/binary.rs	0.00%	2 Missing ⚠️
crates/burn-jit/src/kernel/binary_int.rs	0.00%	2 Missing ⚠️
crates/burn-jit/src/kernel/comparison.rs	0.00%	2 Missing ⚠️
...tes/burn-jit/src/kernel/conv/conv2d/layout_swap.rs	0.00%	2 Missing ⚠️
...urn-jit/src/kernel/conv/deform_conv_transpose2d.rs	0.00%	2 Missing ⚠️
crates/burn-jit/src/kernel/mask/mask_fill.rs	0.00%	2 Missing ⚠️
crates/burn-jit/src/kernel/mask/mask_where.rs	0.00%	2 Missing ⚠️
...tes/burn-jit/src/kernel/quantization/dequantize.rs	0.00%	2 Missing ⚠️
crates/burn-jit/src/kernel/cast/base.rs	0.00%	1 Missing ⚠️
... and 22 more

❌ Your patch check has failed because the patch coverage (0.00%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2742      +/-   ##
==========================================
- Coverage   83.58%   83.57%   -0.01%     
==========================================
  Files         824      824              
  Lines      108340   108453     +113     
==========================================
+ Hits        90553    90639      +86     
- Misses      17787    17814      +27     

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