Release java references in the JNI for calls going from native to Java

AVRCP Target's native avrcp_service heavily relies on JNI calls to get
the current state of media on the device from the Java based Media
Framework. When we make calls from native and receive references to Java
objects we need to be certain we free those references so that the Java
GC can clean up the memory.

We fail to do so in many places, which has led to memory leaks. The
biggest issue is with Bitmap image references that leak and cause a
build up of memory relatively quickly since they're quite large.

This change aims to add DeleteLocalRef() calls to all the Java objects
we create in the JNI. Note that JNI types that represent language
primatives (jint, jbyte, jboolean, etc.) are mapped to native c++ types
and don't need to be freed. But, jobjects, jstr, and arrays all need to
be freed.

Tag: #stability
Bug: 192800249
Test: atest BluetoothInstrumentationTests
Test: Tested with a car that continually makes GetItemAttribute
requests, allowing the memory leak to build up quickly. Showed that the
crashes coming from the leak no longer happen.

Change-Id: I70333640e9e941422223252d2858f96d3a96c8f9
Merged-In: I70333640e9e941422223252d2858f96d3a96c8f9