Import GoogleTest 1.10.0
GoogleTest 1.10.0 is the last official release series planned for GoogleTest.
After 1.10.x, Google is switching GoogleTest to a "release on master" model,
as documented here: https://abseil.io/about/philosophy .
More information about what's captured between releases can be found on the
GitHub release page: https://github.com/google/googletest/releases .