Add PackageManagerInternal mock to prevent NPE

This is a follow up of Idf5d954d89594f7b7a45650ab9173ae16e437dc9.

Bug: 171844163
Bug: 171762932
Test: atest FrameworksServicesTests:com.android.server.am
Change-Id: I821fef336849def8669bb53bfd1cdfde5d5262de
1 file changed