[Fusion] Support multi-precision fusion

[nathanielsimard]

Checklist

• Confirmed that run-checks all script has been executed.
• Made sure the book is up to date with changes in this PR.

Related Issues/PRs

Fix #1694

[laggui]

Man, I need another coffee after looking at all this code ☕

Overall, LGTM! Seems to have really simplified things to move the types to the runtime.

Only have two minor comments below.

[codecov]

Codecov Report

Attention: Patch coverage is 87.71084% with 204 lines in your changes are missing coverage. Please review.

Project coverage is 86.42%. Comparing base (2e4c82f) to head (97a2c4f).
Report is 1 commits behind head on main.

Files	Patch %	Lines
crates/burn-fusion/src/ops/int.rs	90.13%	37 Missing ⚠️
crates/burn-fusion/src/server.rs	46.66%	24 Missing ⚠️
crates/burn-fusion/src/client/mutex.rs	55.76%	23 Missing ⚠️
crates/burn-jit/src/element.rs	0.00%	18 Missing ⚠️
crates/burn-fusion/src/ops/unary.rs	63.41%	15 Missing ⚠️
crates/burn-jit/src/fusion/base.rs	16.66%	15 Missing ⚠️
crates/burn-fusion/src/ops/float.rs	96.61%	14 Missing ⚠️
crates/burn-fusion/src/ops/binary.rs	25.00%	12 Missing ⚠️
crates/burn-fusion/src/ops/boolean.rs	90.62%	12 Missing ⚠️
crates/burn-jit/src/codegen/dialect/gpu/shader.rs	40.00%	9 Missing ⚠️
... and 8 more

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #1718    +/-   ##
========================================
  Coverage   86.42%   86.42%            
========================================
  Files         699      697     -2     
  Lines       81839    82645   +806     
========================================
+ Hits        70729    71429   +700     
- Misses      11110    11216   +106     

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