fix(AutoComplete): some issues

[lukicenturi]

• expose focus and selection range
• fix scrolling issue (reproduce: scroll to bottom, and then filter, then the scroll is not going up, it stucks)
• hide menu when there's no options (and nothing in the menu)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 72.50000% with 11 lines in your changes missing coverage. Please review.

Project coverage is 67.68%. Comparing base (76241a5) to head (0554f9e).

Files	Patch %	Lines
src/composables/dropdown-menu.ts	70.83%	7 Missing ⚠️
...components/forms/auto-complete/RuiAutoComplete.vue	71.42%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #202      +/-   ##
==========================================
+ Coverage   67.67%   67.68%   +0.01%     
==========================================
  Files         103      103              
  Lines       18443    18463      +20     
  Branches      677      678       +1     
==========================================
+ Hits        12481    12497      +16     
- Misses       5962     5966       +4     

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[kelsos]

lgtm