Improved flexibility by removing the Arduino entry points in favor of manual calls to setup/loop that the user can call from their entry point. This is the more common use case for Arudino.
Also added the gtest/gmock_main files to the PlatformIO ignore list since we are not supporting that feature.
Added initial library.json config for PlatformIO
Version will be synced to proper googletest version once the PIO library has been registered and proven out round trip.
