Add entry point at output switcher to do group operation

-Entry point is available only when there are more than 1 connected device
-Add group Slice item when it is available
-Add intent filter in manifest
-Add test case

Bug: 146813761
Test: make -j42 RunSettingsRoboTests
Change-Id: If398b7a31219fd1910503d96fe7593622528c792
5 files changed