Implement more WinUI DatePickerHandler properties

[jsuarezruiz]

Description of Change

Implement more WinUI DatePickerHandler properties:

• Format
• MinimumDate
• MaximumDate
• CharacterSpacing
• Font

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)
• Adds the property to the appropriate interface
• Avoids any changes not essential to the handler property
• Adds the mapping to the PropertyMapper in the handler
• Adds the mapping method to the Android, iOS, and Standard aspects of the handler
• Implements the actual property updates (usually in extension methods in the Platform section of Core)
• Tags ported renderer methods with [PortHandler]
• Adds an example of the property to the sample project (MainPage)
• Adds the property to the stub class
• Implements basic property tests in DeviceTests

Does this PR touch anything that might effect accessibility?

No

[rmarinho]

Shouldn't this handle the Format ?

[rmarinho]

Font and Format seem to be working, but max and min date seems something wrong..

new DatePicker { MinimumDate = DateTime.Now.AddDays(-1), Date = DateTime.Now, MaximumDate = DateTime.Now.AddDays(1) };

this still allows me to select days and months

[hartez]

Font and Format seem to be working, but max and min date seems something wrong..

new DatePicker { MinimumDate = DateTime.Now.AddDays(-1), Date = DateTime.Now, MaximumDate = DateTime.Now.AddDays(1) };

this still allows me to select days and months

This is a limitation of the WinUI DatePicker; it can only restrict the selectable years: https://docs.microsoft.com/en-us/windows/winui/api/microsoft.ui.xaml.controls.datepicker?view=winui-3.0#date-values

So the best we can do out of the box is set MinYear and MaxYear. Hopefully at some point we can include support for the CalendarDatePicker, where MinimumDate/MaximumDate is more useful.