Merge auto scrolling container with scrolling container

[MyreMylar]

Since there wasn't that much code left in the auto scrolling container anyway it seems easier just to merge this functionality into the base container and turn it on by default with a parameter to control turning it off as is needed.

[codecov]

Codecov Report

Attention: Patch coverage is 95.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 96.25%. Comparing base (371b0f1) to head (67384e1).

Files	Patch %	Lines
pygame_gui/elements/ui_scrolling_container.py	94.73%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #575      +/-   ##
==========================================
- Coverage   96.26%   96.25%   -0.01%     
==========================================
  Files          89       89              
  Lines       13156    13153       -3     
==========================================
- Hits        12665    12661       -4     
- Misses        491      492       +1     

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[MyreMylar]

will do this simple functionality merge for now - for the UIForm PR and further testing - but will likely swap it over in there and then remove it entirely.