Encapsulate PackageSetting fields

Auto-refactoring of the fields inside PackageSetting so that they can
be accessed solely through the new PackageState interface.

Does not migrate Object fields that are made immutable through the
PackageState implementation since that could easily break something.

Bug: 173455397

Test: atest com.android.server.pm

Change-Id: I7e4fe07ab77634e1e6a77daf856fa856931c1c97