Bugfix: Disconnect callbacks on object deletion in special functions from event_utils

[Czaki]

Fixes/Closes

Closes #5808

Description

Adds cleaning callback steps on object deletion and adds proper tests.

References

Type of change

• Bug-fix (non-breaking change which fixes an issue)

How has this been tested?

• example: added tests to cover the bug and fix
• example: all tests pass with my change

Final checklist:

• My PR is the minimum possible work for the desired functionality
• I have commented my code, particularly in hard-to-understand areas

[codecov]

Codecov Report

Merging #5826 (08ef873) into main (d8dd1d2) will increase coverage by 0.02%.
The diff coverage is 100.00%.

❗ Current head 08ef873 differs from pull request most recent head 4c49c72. Consider uploading reports for the commit 4c49c72 to get more accurate results

@@            Coverage Diff             @@
##             main    #5826      +/-   ##
==========================================
+ Coverage   89.90%   89.93%   +0.02%     
==========================================
  Files         615      616       +1     
  Lines       52322    52372      +50     
==========================================
+ Hits        47041    47101      +60     
+ Misses       5281     5271      -10     

Impacted Files	Coverage Δ
napari/utils/events/event.py	86.06% <ø> (ø)
napari/utils/events/_tests/test_event_utils.py	100.00% <100.00%> (ø)
napari/utils/events/event_utils.py	100.00% <100.00%> (+4.76%)	⬆️

... and 4 files with indirect coverage changes

[psobolewskiPhD]

@Czaki I cleaned up the title and OP plus the comment.

[Czaki]

I have updated the title as methods is the name for functions bound to the class. I have hope that I do not break the title. Could you check?

[jni]

There's a stray comment, pretty sure it was unintentional but I've left the removal as a suggestion. Otherwise, 👍

[Czaki]

@jni read comment in the first function. I may copy it to all. The general problem is that the proper way to do this is to use finalize, but it causes segfaults. I have a hope that Qt6 may work for this better, so I prefer not to remove it but left commented until drop qt5/