Add dialog for recommended controls

The dialog can only be requested if the package of the controls provider is
currently in the foreground.

This is accomplished by querying Activity Manager about the
UidImportance of that package. Added
android.permission.PACKAGE_USAGE_STATS to SystemUI for this.

Test: atest
Test: manual
Fixes: 149410221

Change-Id: Ifdf479d8dbc70502da95d362e3bfd60ad3c561fb