Add support for A/B (Seamless) System Updates

Loosely based on:
https://github.com/LineageOS/android_packages_apps_CMUpdater/commit/0465cb691de5acd2f459ce0687b988ddf050b354
12 files changed
tree: fb890e263e0f3256564d5874729af493e59ae180
  1. res/
  2. src/
  3. Android.mk
  4. AndroidManifest.xml