Fix menu scrolling when a new plugin is added

[chapulina]

🦟 Bug fix

• Closes Can't scroll to newly added plugin #200

Summary

Scrolling the right split has been broken since #194. It only took me a year to come back and fix it 🙃

There were 2 issues:

• The scope when setting Layout.minimumWidth
• The logic meant to check if an item is collapsed was using its current height, instead of its Layout.maximumHeight

I hope I'm not introducing yet another bug. I think all use cases mentioned in #194 are covered here, but I'd appreciate if the reviewers really try to break this.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

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🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸

[codecov]

Codecov Report

Merging #368 (c45bedf) into ign-gui3 (fc2f870) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           ign-gui3     #368   +/-   ##
=========================================
  Coverage     65.96%   65.96%           
=========================================
  Files            29       29           
  Lines          3191     3191           
=========================================
  Hits           2105     2105           
  Misses         1086     1086           

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[osrf-triage]

This pull request has been mentioned on Gazebo Community. There might be relevant details there:

https://community.gazebosim.org/t/new-ignition-releases-2022-04-13-fortress-edifice/1367/1