Add autosuggest filter to modify list container

[JakePT]

Description of the Change

Add support for 2 'filter' functions modifying Autosuggest suggestions:

• epAutosuggestListItemsHTMLFilter Filters the HTML that's added to the list when the suggestions are updated.
• epAutosuggestElementFilter Filters the container element before it's added to the DOM.

Documentation with examples is included for both, and documentation with an example is also included for the existing epAutosuggestItemHTMLFilter function (closes #2776).

Closes #2811

How to test the Change

Implement the examples from the documentation updates and confirm that they work as expected.

Changelog Entry

Added - Autosuggest: filter the HTML of all results by defining a window.epAutosuggestListItemsHTMLFilter() function in JavaScript.
Added - Autosuggest: filter the container element by defining a window.epAutosuggestElementFilter() function in JavaScript.
Added - Documentation for Autosuggest JavaScript filters.

Credits

Props @JakePT

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[felipeelia]

Let's add #2909 to these docs as well @JakePT :)