Expose some package APIs for ART

This was separated out to make review easier. Applies @SystemApi
to expose a subset of PackageState and its child type APIs.

Bug: 235462722
Bug: 246609797
Bug: 244444049
Bug: 229089418
Bug: 229090204
Bug: 229090094

Test: presubmit

Change-Id: Ifc0ee3584347a79fbb0e7815d42bac6d2c2f3a4a