Cube: first ported kernel + comptime support + variable reuse + cleanup

[louisfd]

The convolution2d kernel has been ported to Cube

[codecov]

Codecov Report

Attention: Patch coverage is 68.02974% with 172 lines in your changes are missing coverage. Please review.

Project coverage is 86.44%. Comparing base (76fe0ed) to head (d42426a).
Report is 7 commits behind head on main.

Files	Patch %	Lines
crates/burn-jit/src/kernel/conv/conv2d.rs	38.63%	81 Missing ⚠️
crates/burn-cube/src/language/comptime.rs	45.83%	13 Missing ⚠️
crates/burn-cube/tests/language/cast_elem.rs	45.45%	12 Missing ⚠️
crates/burn-cube/src/language/operation/binary.rs	0.00%	10 Missing ⚠️
crates/burn-cube/src/language/element/uint.rs	12.50%	7 Missing ⚠️
crates/burn-cube/tests/language/if.rs	0.00%	7 Missing ⚠️
crates/burn-cube/tests/language/if_else.rs	86.00%	7 Missing ⚠️
crates/burn-cube/src/language/branch.rs	86.66%	6 Missing ⚠️
...es/burn-cube/src/language/operation/assignation.rs	0.00%	6 Missing ⚠️
crates/burn-cube/src/language/element/numeric.rs	20.00%	4 Missing ⚠️
... and 13 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1797      +/-   ##
==========================================
+ Coverage   86.39%   86.44%   +0.04%     
==========================================
  Files         737      741       +4     
  Lines       85883    86114     +231     
==========================================
+ Hits        74202    74441     +239     
+ Misses      11681    11673       -8     

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[nathanielsimard]

LGTM !