refactor(combo): Use key-bindings controller

[rkaraivanov]

Closes #1850

This commit migrates the combo component to use
the general key-bindings controller from the library. Aside from unifying the implementation across components this also improves several behaviors of the combo:

• Keyboard events inside the combo are no longer "swallowed".
• Tab navigation is more natural, i.e. there are no longer 2 tab stops per combo component.

Updated the combo test suite to accommodate for the changes.

[ddaribo]

When disableFiltering is true (single-select is false), the popup is not closed and focus is not moved to the input on Up key press from the first item:

This is a different behavior than if single-select is true. This also occurs before the refactoring.

[rkaraivanov]

@ddaribo @dkoleva-infra

I guess that is a bug/mismatch in the combo configuration. I did not find any relevant information
in the specification about what behavior should we expose, so now the combo will close its dropdown and move focus back into the main input if single-selection or disable-filtering are set.

@dkoleva-infra
If that is acceptable, can you update the specification with the new behavior?