DSU enhancement (4/N)

* Support hiding notification
  This allows the client to provide customized UI
  to enter/exit DSU without using the notifications
  from the status bar.

Bug: 277691885
Test: adb shell am start-service --user 0 \
  -n com.android.dynsystem/com.android.dynsystem.DynamicSystemInstallationService \
  -a android.os.image.action.HIDE_NOTIFICATION
Change-Id: I3f51e6caf0d3b336a71b6154d644f89624cd9491