Refactor/cube/mutability

[nathanielsimard]

Now arrays and tensors are passed by reference to functions, since they don't implement copy anymore.

[codecov]

Codecov Report

Attention: Patch coverage is 47.15026% with 102 lines in your changes missing coverage. Please review.

Project coverage is 84.56%. Comparing base (f9ec2e1) to head (f13d063).
Report is 3 commits behind head on main.

Files	Patch %	Lines
crates/burn-jit/src/kernel/contiguous.rs	41.26%	37 Missing ⚠️
...rates/burn-cube/src/frontend/element/vectorized.rs	0.00%	8 Missing ⚠️
crates/burn-cube/src/frontend/subcube.rs	27.27%	8 Missing ⚠️
crates/burn-jit/src/kernel/conv/conv2d.rs	16.66%	5 Missing ⚠️
crates/burn-cube/src/frontend/element/bool.rs	0.00%	4 Missing ⚠️
crates/burn-cube/src/frontend/element/float.rs	0.00%	4 Missing ⚠️
crates/burn-cube/src/frontend/element/int.rs	0.00%	4 Missing ⚠️
crates/burn-cube/src/frontend/element/tensor.rs	33.33%	4 Missing ⚠️
crates/burn-cube/src/runtime_tests/subcube.rs	0.00%	4 Missing ⚠️
crates/burn-cube/src/frontend/element/array.rs	25.00%	3 Missing ⚠️
... and 12 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1934      +/-   ##
==========================================
- Coverage   85.09%   84.56%   -0.54%     
==========================================
  Files         791      793       +2     
  Lines       93319    93859     +540     
==========================================
- Hits        79412    79370      -42     
- Misses      13907    14489     +582     

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[louisfd]

lgtm (shallow review, but i'll merge it in my stuff to see if it works well)