Adding test for loading JNI libraries in individual tests

Add a bivalent test that uses a native library.

Also added a utility method to load it in the same way on both
sides.

Bug: 318393625
Bug: 323931246

Test: run-ravenwood-tests.sh
Test: atest RavenwoodBivalentTest_device
Change-Id: I270058c15f718ff20640681742035e33e5e015a1