Fix widget scrolling with magicgui>=0.5

[dstansby]

magicgui 0.5 broke the scrollbars in cellfinder-napari. This was kind of unsurprising though, because the previous solution in cellfinder-napari was very hacky, and involved using private API in magicgui (always a bad idea...). This PR fixes that.

The fix is simple, and robust against future changes in magicgui - take the QtWidget magicgui provides, wrap it in a ScrollArea and return the ScrollArea.

Please could the reviewer manually check the scrollbar works with this PR and magicgui==0.5.1?

[dstansby]

😱 it seems like this breaks layer selection, so moving to draft

[deprecated-napari-hub-preview-bot[bot]]

Preview page for your plugin is ready here: https://preview.napari-hub.org/brainglobe/cellfinder-napari/127 Created: 2022-06-27T10:13:37.969835

[codecov-commenter]

Codecov Report

Merging #127 (c7d1cc5) into main (2a44950) will decrease coverage by 0.31%. The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #127      +/-   ##
==========================================
- Coverage   81.57%   81.25%   -0.32%     
==========================================
  Files          15       15              
  Lines         662      667       +5     
==========================================
+ Hits          540      542       +2     
- Misses        122      125       +3     

Impacted Files	Coverage Δ
cellfinder_napari/detect/detect.py	48.33% <0.00%> (-3.40%)	:arrow_down:
cellfinder_napari/detect/thread_worker.py	96.15% <0.00%> (+0.50%)	:arrow_up:

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[dstansby]

😱 it seems like this breaks layer selection, so moving to draft

I've opened an issue upstream for this: https://github.com/napari/napari/issues/4749

[adamltyson]

going to close this as magicgui now supports scrollbars.