Drop inserting in capture (changing in-place) and instead just add and then remove frames

[psobolewskiPhD]

Closes: #231

So in napari/napari#7150 event handling order was changed in napari.
This is making the key frame list manipulations for inserting a replacement frame not work correctly when the list change event callbacks trigger. I tried passing position='first' in the .connect() in various places and could not get it to resolve properly -- it's events of the SelectableEventedList, which are on the napari side I think.

I also tried to keep the name of the frame when insert=False, but the hash is still different so selection still fails.

In this PR I work around all this event stuff by removing the insert kwarg on capture_frame and no longer edit the frame in-place when replacing. Instead, the new frame is added and previous is removed.
Note that the frame number was already incrementing even when replacing a frame (insert=False) and because one can re-order frames, the numbers lose meaning.

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 86.08%. Comparing base (ba8ab53) to head (d1a07a0).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
napari_animation/_qt/animation_widget.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #233      +/-   ##
==========================================
- Coverage   86.24%   86.08%   -0.16%     
==========================================
  Files          26       26              
  Lines        1076     1071       -5     
==========================================
- Hits          928      922       -6     
- Misses        148      149       +1     

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[alisterburt]

Superseded by #234 - thanks for delving though!