Log NNAPI VTS test case to logcat

Sample output:

    I VtsHalNeuralnetworksV1_2TargetTest: [Test Case] TestGenerated/GeneratedTest.Test/nnapi_sample_all_add BEGIN
    ...
    I VtsHalNeuralnetworksV1_2TargetTest: [Test Case] TestGenerated/GeneratedTest.Test/nnapi_sample_all_add END

Bug: 159060565
Test: VtsHalNeuralnetworksV1_0TargetTest (inspected logcat output)
Test: VtsHalNeuralnetworksV1_1TargetTest (inspected logcat output)
Test: VtsHalNeuralnetworksV1_2TargetTest (inspected logcat output)
Test: VtsHalNeuralnetworksV1_3TargetTest (inspected logcat output)
Change-Id: Ic1a0c90e0853ca84dd925d0f7df65e159bb284aa