feat: categorical slider [WIP]

[tlambert03]

This adds a new QCategoricalSlider and QLabeledCategoricalSlider, when you want a slider to select from a discrete set of objects (rather than numbers). Similar to a combobox I guess, but easier to change between all the values.

API still needs consideration

from qtpy.QtWidgets import QApplication

from superqt.sliders import QLabeledCategoricalSlider

app = QApplication([])
slider = QLabeledCategoricalSlider(
    categories=["dog", "cat", "elephant", "bird", "fish"]
)
slider.show()
slider.categoryChanged.connect(lambda category: print(category))
app.exec()

Screen.Recording.2024-10-15.at.6.00.36.PM.mov

edit: the label is now a combobox to allow two-way editing

[codecov]

Codecov Report

Attention: Patch coverage is 69.53642% with 46 lines in your changes missing coverage. Please review.

Project coverage is 85.95%. Comparing base (952ac33) to head (bb2b79d).

Files with missing lines	Patch %	Lines
src/superqt/sliders/_categorical_slider.py	35.13%	24 Missing ⚠️
src/superqt/sliders/_labeled.py	80.70%	22 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #256      +/-   ##
==========================================
- Coverage   87.09%   85.95%   -1.15%     
==========================================
  Files          46       47       +1     
  Lines        3433     3503      +70     
==========================================
+ Hits         2990     3011      +21     
- Misses        443      492      +49     

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[Czaki]

Maybe also add an enum version of it?