API for listening for automated apps.

Requires the caller to hold ROLE_HOME

Keeping the API close to LauncherApps.Callback and exposing it via
the extensions library.

Caveats:
 - Currently we only have UIDs in VDM, not package names. Multiple
   packages may share the same UID but this is very rare and hardly
   a short-term blocker

Flag: android.companion.virtualdevice.flags.computer_control_access
Bug: 440353845
Bug: 440355882
Test: atest & manual & presubmit
Change-Id: I469cf38b49eecb063687a5593889791b3948c0df