SystemUI: Refactor for album art, icon and playback

* Removed unnecessary bitmap scaling ops in controller - saves upto 10% CPU.
* Removed ineffective album art retry loop in controller. It was ineffective since
  partial mediadata was never updated in helper. Move logic to media session helper.
  Highly improves album art rendering chances.
* Streamlined playback path. Checks removed in onMediaMetadataChanged() since
  requestUiUpdate() will necessary update even for media metadata update.
* Fetch new album art and icon only if there are changes.
* Do pause stale check on chip interaction, media metadata update and playback
  update - improves UX.
* Add padding before compact icon; matches full chip and gives better aesthetics.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>

Author: neobuddy89