Adds the test fixture support and converts a few tests to exercise the
code and show how it works.
Bug: 181070625
Test: m nothing
Change-Id: I0a2b40fff93b6041f9aa8c4ef0aba91da1bc8bf3
There is no need to create a separate buildDir for each test
file, use TestMain to create a global one for the package.
Test: all soong tests
Change-Id: I435ee7aa88b7e0bb8ccc1ba79f82833a7accf3e9