Make system-signed apps implicitly force-queryable

Apps that are signed the same as the system can be considered part of
the system and so are implicitly force queryable. This includes things
like common system providers.

Bug: 136675067
Test: atest AppSecurityTests AppEnumerationTests AppsFilterTest
Change-Id: I9cedc0e77b7941d8d354c9e2a20d8309174efcd6