Create CTS tests for AssetManager hardening

When a package accesses the resources of a different, incrementally
installed package, the process must not crash. Instead, resource
retrieval methods return null results or throw a combination of
Resources.NotFoundExceptions and IOExceptions depending on how callers
currently expect to handle failures of those methods.

ResourcesHardeningTest verifies that if all necessary blocks are served
to the device resolution works as expected, and if some necessary
blocks are missing, the process does not crash and instead falls back
to default functionality.

Bug: 180033566
Test: atest ResourcesHardeningTest
Change-Id: I275f2046e4e42cbb9b7e9d27b311155ee93a6519