Make label types searchable and filterable

[simont2k]

The ComboBox for label types now allows text input which is used for case-insensitive search and filtering.
After entering the text in the field, the arrow keys can be used to select from the filtered options.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.07%. Comparing base (2b093f0) to head (c3d3d99).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #26      +/-   ##
==========================================
+ Coverage   87.94%   88.07%   +0.12%     
==========================================
  Files           9        9              
  Lines         929      939      +10     
==========================================
+ Hits          817      827      +10     
  Misses        112      112              

Flag	Coverage Δ
unittests	88.07% <100.00%> (+0.12%)	⬆️

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