feature: show graph legend in more situations

[ClementTsang]

Description

A description of the change, what it does, and why it was made. If relevant (e.g. UI changes), please also provide screenshots/recordings:

This PR makes it so that instead of always just hiding the entire legend if it's too big for the current size, we instead show less parts of the legend to make it fit. For example, if it's too tall, we just show less entries. If it is too wide, but other entries still would fit, we truncate the entries that are too long so they fit.

This is somewhat helpful because in the memory widget, the GPU entry at the moment is causing the legend to hide in situations where it used to not. We can also do more work to make that better, but IMO not always hiding the legend also makes sense to have in general.

Issue

If applicable, what issue does this address?

Closes: #1999

Testing

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• Windows
• macOS (specify version below)
• Linux (specify distro below)
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Checklist

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• If this PR adds or changes a dependency, please justify this in the description
• If this is a code change, areas your change affects have been linted using (cargo fmt)
• If this is a code change, your changes pass cargo clippy --all -- -D warnings
• If this is a code change, new tests were added if relevant
• If this is a code change, your changes pass cargo test
• The change has been tested to work (see above) and doesn't appear to break other things
• Documentation has been updated if needed (README.md, help menu, docs, configs, etc.)
• There are no merge conflicts
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Other

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[codecov]

Codecov Report

❌ Patch coverage is 96.74797% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.62%. Comparing base (ddd8d87) to head (470bbc3).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/canvas/widgets/network_graph.rs	50.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2031      +/-   ##
==========================================
+ Coverage   60.43%   60.62%   +0.18%     
==========================================
  Files         122      122              
  Lines       16959    17049      +90     
==========================================
+ Hits        10250    10336      +86     
- Misses       6709     6713       +4     

Flag	Coverage Δ
macos-14	46.85% <86.17%> (+0.23%)	⬆️
ubuntu-24.04	59.40% <96.74%> (+0.20%)	⬆️
windows-2022	46.41% <86.17%> (+0.23%)	⬆️

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