Implement Task Manager UI

This adds the dialog and a quicksettings tile entrypoint to show the
user apps which have foreground services running.

TODOs: Use security footer instead of quicksettings tile
       Implement the missing UX of the stopped FGS
       Tests

Test: atest SysetmUITests
Bug: 201579707

Change-Id: I2185a22b789404b97e98a16c11c0a296159ddd89