Settings: Apply system tint to first private storage

* Instead of always using the default tint, we get the current
  tint from system and use that for the first private storage
* Refactor the code away from hardcoded colors

Solves:
https://gitlab.com/LineageOS/issues/android/issues/1130

Change-Id: I8eca661224ee32147fd5fc95e1fa8a7d4589697f