[DatePicker] add divider to DatePicker

[manabu-nakamura]

Is your feature request related to a problem? Please describe.
The DatePicker has no divider.

https://m3.material.io/components/date-pickers/overview
https://m3.material.io/components/date-pickers/specs
https://m3.material.io/components/date-pickers/guidelines
The DatePicker has a divider.

Describe the solution you'd like
Add a divider to the DatePicker.

Is your feature request related to a problem? Please describe.
The DatePicker has no divider (it doesn't have Cancel button and OK button).

https://m3.material.io/components/date-pickers/specs
The DatePicker has a divider (it has Cancel button and OK button).

Describe the solution you'd like
Add a divider to the DatePicker.

Additional context
The position of divider (A) and (B) are different.
(A) https://m3.material.io/components/date-pickers/specs

(B) https://m3.material.io/components/date-pickers/guidelines