[WIP] Run clippy fix on clippy::pedantic errors

[crutcher]

Checklist

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

Changes

This sits on top of #3200

I enabled pedantic = "deny"; ran cargo clippy --fix; then disabled and cleaned up.

[codecov]

Codecov Report

Attention: Patch coverage is 71.89189% with 312 lines in your changes missing coverage. Please review.

Project coverage is 82.08%. Comparing base (e21cc7e) to head (15a97de).
Report is 46 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/onnx-ir/src/ir.rs	4.87%	39 Missing ⚠️
crates/burn-cubecl-fusion/src/shared/kernel.rs	0.00%	23 Missing ⚠️
crates/burn-router/src/runner.rs	79.43%	22 Missing ⚠️
...ates/burn-train/src/renderer/tui/metric_numeric.rs	0.00%	16 Missing ⚠️
crates/burn-train/src/renderer/tui/renderer.rs	0.00%	15 Missing ⚠️
crates/burn-cubecl-fusion/src/shared/io.rs	0.00%	9 Missing ⚠️
crates/burn-remote/src/server/base.rs	0.00%	7 Missing ⚠️
.../burn-dataset/src/source/huggingface/downloader.rs	0.00%	6 Missing ⚠️
crates/burn-ndarray/src/ops/simd/conv.rs	25.00%	6 Missing ⚠️
crates/burn-tch/src/ops/base.rs	14.28%	6 Missing ⚠️
... and 77 more

❌ Your patch check has failed because the patch coverage (71.89%) 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    #3206      +/-   ##
==========================================
- Coverage   82.22%   82.08%   -0.14%     
==========================================
  Files         962      963       +1     
  Lines      122572   122762     +190     
==========================================
- Hits       100779   100769      -10     
- Misses      21793    21993     +200     

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[github-actions]

This PR has been marked as stale because it has not been updated for over a month

[laggui]

This mostly seems to fix more aggressive clippy lints along with typos / formatting in docstrings. Not entirely against, though I feel some lints are probably more opiniated than anything so we might have to be careful.

One thing I am not sure about is the usage of #[must_use]. I also think its usage should be informed to indicate specific types that are "important" (e.g., results that should not be ignored, or types with custom drop implementation). In other words, this is more advice to the usage than anything. I did not review the whole set of changes, but the few additions of must_use seemed to make sense at first glance.

@crutcher did you actually want to go through with some of these suggestions, or were you mostly fiddling with the lints? In other words, should this be closed or not 😅 )

[crutcher]

I think most of these suggestions are good ideas; and I'd like to move forward by turning on specific extra lints, one at a time, and fixing them.