Refinements to initial RingtoneSelection.

    * Rename SOUND_SOURCE_DEFAULT to SOUND_SOURCE_UNSPECIFIED.
    * Add SOUND_SOURCE_SYSTEM_DEFAULT.
    * likewise for vibration.
    * Rename VIBRATION_SOURCE_APPLICATION_PROVIDED to
       VIBRATION_SOURCE_APPLICATION_DEFAULT.
    * Handle legacy system default Uris when parsing Uris.
    * Handle userIds in Uri methods / provide canonicalization.
    * Canonicalize Uris when building a RingtoneSelection. This only
      affects file:// URIs: this is uri canonicalize,
      not ContentProvider.canonicalize.

Bug: 272282867
Test: unit
Change-Id: Ibe202f0c4782e4be1c26b4caeccbc33419569969