Exclude headless packages from being scanned as stopped.

With the enabling of putting all system apps in stopped state, we want
to automatically exclude all packages that don't have a launcher entry,
since those packages don't have a clean way for a user to "unstop" them.
This is a rather conservative approach, that may be revisited in the
future.

Bug: 269129704
Test: Manual inspection no headless packages are stopped

Change-Id: Ic2ea4b37d34ebcfea912e65e1bd0f2e1150a3daa