[Output Switcher] [Group by Type] Add MediaItem to store data

Apply new class MediaItem to store item in the list, this change will
not have impact on layout and functionality should remain the same.
This is first refactor stage of making OutputSwitcher support custom
item, which will be used to apply grouping devices by type request.

design: go/output-switcher-custom-items

Bug: 255124239
Test: atest MediaOutputAdapterTest MediaOutputControllerTest MediaOutputBaseDialogTest MediaOutputDialogTest
Change-Id: Ibda4f0af1204d9e9eb48a3137d50ab591a276319
8 files changed