Introduce RingtoneSelection for carrying ringtone preference information.

Notably, this class isn't intended to support setting a VibrationEffect -
such an effect should only be set via a Uri pointing to a serialized one.
The "effect" setting on the vibration source refers to a contextual one
(such as one set on a notification channel).

Bug: 272282867
Test: cts
Change-Id: Ide5cccbd3fbee4553885eaa8b80accd1169a9cd7