feat: Add support for inputTabIndex prop

[dshafik]

This small PR adds support for an inputTabIndex prop to allow adding a tabIndex to the input. Note that to verify in the playground you need to use the dev tools and view the input element directly. Having a tabIndex will also trigger the onBlur handler to hide the popup.

[dshafik]

~I think for this to be complete, the behavior when tabbing to the next field must be fixed to hide the popup.~

done.