SDK / exoplayer

This change deprecates `PlayerView.setUseArtwork(boolean)` and
introduces `setArtworkDisplayMode(mode)` and
`artworkDisplayMode="off|fit|fill"` instead.

- off: no artwork is displayed (like deprecated useArtwork=false)
- fit: letterbox like media (like deprecated useArtwork=true)
- fill: scales the artwork to fill the entire width/weight of the player view

#minor-release

PiperOrigin-RevId: 534167226
(cherry picked from commit 7f3f2fe0758e083cc5baf8781b1f1be20d32f052)