Update AppClips to handle multi-user.

- All NoteTask components needing to interact with the Bubbles APIs should use the new NoteTaskBubbleService if there is a chance that the component can be launched as a non system user.
- As a side effect of this change, the shortcut/widget code is also simplified.
- Used the singleUser manifest attribute to always only start the services under the correct SysUI user as an extra safeguard.

Bug: 282763432
Test: atest SystemUITests
Change-Id: I520c1881e550e1aa8444b9177248913843e56720