Tightening app component alias

See the following slide for the details.
https://docs.google.com/presentation/d/1ZAVvrySobhD0bcWZwk3vkH9wxtxg1iPpApVc882VARY/edit#slide=id.ged9d1f364e_0_0

- Also fix the test -- previously, even though we had three separate
test APKs, they were all executed as the main APK, beucase they
all instrumented the main APK. Now they each instrument their own package.

Bug: 196254758
Test: atest ComponentAliasTests ComponentAliasTests1 ComponentAliasTests2
Change-Id: I356d38b54df952ec5a30ed73d9dca5c0a71ad06e