[Media] Adds building block composable elements.

This CL adds:
- Metadata: the title and subtitle
- Secondary action: a simple icon button
- Play/pause action: a larger icon button with animated corners
- Output switcher chip: a simple icon + text button

Please refer to the screenshot at screen/7brg4TZcqrK9dMK

Bug: 397989775
Test: tested in testbed app with fake data, see b/397989775#comment2 for
a screen recording of the entire thing in action in the compose gallery
app
Flag: EXEMPT none yet, code is currently unused

Change-Id: I4863170ab96b48db300f23e1672bfd76a0f8ea15