Change NNAPI Memory to ref-counted SharedMemory -- runtime Bug: 179906132 Test: mma Test: NeuralNetworksTest_static Test: presubmit Change-Id: Icf335370631e34730cf0fe6a11b850884e50ac53 Merged-In: Icf335370631e34730cf0fe6a11b850884e50ac53 (cherry picked from commit b470600e8d7dd65738b0680e11f852062fee0494)