WEBDEV-8119 Add basic combo-box component

[latonv]

Creates a new combo-box component in the labs directory. This component is intended to act as a flexible form control allowing users to select from predefined options, search & filter those options with text input, and optionally enter their own custom values entirely.

To that end, the component supports three levels of behavior:

• select-only: Functions like a <select> dropdown widget, disallowing text input and requiring a selection to be made from the options presented.
• list (default): Retains the dropdown behavior as above, but also allows the dropdown options to be filtered by entering a partial value in the widget's text box. It can still only take on values from the predefined options. Implements W3C recommendations for the combobox role with list autocomplete
• freeform: Presents a filterable dropdown of options like list but does not restrict its held values to these options, instead allowing any text value to be held in the widget. This is essentially just a text input with autocomplete suggestions.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.61489% with 29 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.15%. Comparing base (bd89dc0) to head (e9bfb0b).

Files with missing lines	Patch %	Lines
src/elements/ia-combo-box/ia-combo-box.ts	90.20%	9 Missing and 20 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #24       +/-   ##
===========================================
+ Coverage   68.42%   87.15%   +18.73%     
===========================================
  Files           5        7        +2     
  Lines          57      366      +309     
  Branches        7       87       +80     
===========================================
+ Hits           39      319      +280     
- Misses         15       24        +9     
- Partials        3       23       +20     

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[jbuckner]

This looks really nice! 👏

Since this is going into production pretty soon, what do you think of moving it out of labs and into the main elements section?

[rebecca-shoptaw]

Looking great! One note re: possible CSS structure to avoid too many variables (and any in :host that aren't also reflect in theme-styles.ts which I feel should be our standard).

[github-actions]

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