Update DatePicker widget and its related dialog

- the old DatePicker widget is still there for obvious layout compatibility reasons
- add a new delegate implementation for having a new UI
- use the new delegate only for the DatePickerDialog (which does not need to be
the same)
- added support for Theming and light/dark Themes
- added support for RTL
- added support for Accessibility
- verified support for Keyboard
- verified that CTS tests for DatePicker are passing (for both the legacy and the
new widgets)

Also added a new HapticFeedbackConstants.CALENDAR_DATE and its related code for
enabling day selection vibration

Change-Id: I256bd7c21edd8f3b910413ca15ce26d3a5ef7d9c