[MaterialDatePicker] Support different calendar input modes

[safa007]

Is your feature request related to a problem? Please describe. The current MaterialDatePicker forces you to select day, month, and year and is not customizable so that a user can only select day and month or month and year.

Describe the solution you'd like Support different input modes where a user can select just day and month or month and year.

Describe alternatives you've considered We needed to build our own custom Month/Year picker that uses DialogFragment. But we'd prefer not to build custom views for things like this.