Add setVoicemailRingtoneUri() and setVoicemailVibrationEnabled()

This CL allows the default dialer to modify the voicemail ringtone.
All settings except the voicemail provider and voicemail nubmer can
be moved to the dialer after this CL.

Bug: 34626472
Fixes: 34626472
Test: CtsTelephonyTestCases TelephonyManagerTest
    testVoicemailRingtoneSettings and testVoicemailVibrationSettings

Change-Id: I5dd1e5ac8c358b09ff9a98051c429dba758c04a4