Send notifications for media type Playlist

Add tests to check if the notification is received by the client app.

Bug: 165948693
Test: atest ClientPlaylistTest
Change-Id: Ic611ba1c4a6430ab10b05320f7e37a7e7f4e662a
Merged-In: Ic611ba1c4a6430ab10b05320f7e37a7e7f4e662a
(cherry picked from commit cf4b1ddb9215a363f66f9ce6934bd939500993cc)
2 files changed