R1:948d69364aae

Manage date control enabled state as part of DateControlValue

Summary: Ref T8024. Allow `DateControlValue` to manage enabled/disabled state, so we can eventually delete the copy of this logic in `DateControl`.

Test Plan:
- Used Calendar ApplicationSearch queries to observe improved behaviors:
- Error for invalid start date, if enabled.
- Error for invalid end date, if enabled.
- Error for invalid date range, if both enabled.
- When submitting an invalid date (for example, with the time…