libandroidfw: Add new support for shared libraries

This adds support for shared resource libraries in the new
ResTable/AssetManager implementation.

The dynamic package map encoded in resources.arsc is parsed
and stored with LoadedArsc, and combined to form a resolved table
in AssetManager2.

Benchmarks show that this implementation is an order of magnitude
faster on angler-userdebug (make libandroidfw_benchmarks).

Test: libandroidfw_tests
Change-Id: I57c80248728b63b162bf8269ac9495b53c3e7fa0