ART: Add JNI local details for FollowReferences

Give details for the thread.

Stack depth and method are currently approximated (as
bottom of the stack), as the RootInfo does not have that
information.

Bug: 31385354
Test: m test-art-host-run-test-913-heaps
Change-Id: I8e51415a02678c55b687144b4cb749c4105bd3c1