[Media] Adds seek bar component.

- Seek bar component, including its track and thumb; including it's
  "squiggle" wave animation
- Next/prev buttons

Please refer to the screen recording at b/397989775#comment2

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: I5d6ac40d53874eaaf1467a907be820f0d3b7a322