Change NNAPI VTS to use TEST_P to iterate across all service instances

This CL removes a dependency on the VTS test runner by dynamically
discovering all NN HAL service instances in the gtest binary itself,
and runs through all service instances with parameterized tests.

This CL converts TEST_F cases to TEST_P cases, where the test parameter
is the name of the service instance. For existing TEST_P cases (such as
the generated test cases), the service instance name is made to be the
first test parameter.

This CL enables the NN VTS tests to be more portable, e.g., they can
run directly as a presubmit test.

Fixes: 124540002
Test: mma
Test: VtsHalNeuralnetworksV1_*TargetTest (with sample-all)
Test: cd $ANDROID_BUILD_TOP/hardware/interfaces/neuralnetworks && atest
Change-Id: I1e301d7c9f9342bb8f35a267bef180f510944b19