Tackling a few issues that have risen from the Datepicker refactor:
- [x] fixed issue with clear button not appearing
- [x] fixed issue with backspacing
- [x] fixed issue calendar 'cursor' staying in sync with month changes. (a11y)
- [x] issue with focus returning to datepicker when other inputs are selected.
- [x] add usePortal prop to render the calendar into a portal to avoid it being cut off by overflow-hidden containers.