Tags Property Editor: Remove tags with keyboard backspace/delete

[engijlr]

Added keyboard support for tag deletion and improved input navigation:

-Tags can now be deleted when focused by pressing the Backspace key.
-Added logic to exit the input field when no text is provided, improving keyboard navigation.

[engijlr]

Update: Better tag focus handling and corrections from the last PR

-Added logic to find the current focusable tag using tabindex.
-Only one tag can be focused at a time (tabindex="0"), the rest are skipped (tabindex="-1").
-Makes it easier to move between tags with the keyboard and delete the right one.

*No need to tab through every single tag.

[leekelleher]

Tested out, it's a great improvement... and excellent to fix the keyboard trap, and the arrow navigation is a nice touch! 🚀

I've made a few amends to your PR. I found that we could remove the "enteredTagsWrapper" container tag by adding the tabindex attribute to the uui-tag items directly. Also removed the needed to switch the tabindex between -1 and 0, as the browser can handle that part.

I feel there are further UI refactoring we can do to make the Tags input even more accessible, but let's get this improvement in for v16.3 and we look at enhancements for v17.