AT4-1147 update googletest for PANDA
Update the thirdparty googletest package to a newer version. This is a part of the bigger drive to migrate the code to C++17.
- The code changes included in this MR now allow the update of googletest based on the version number that is mentioned in googletest.cmake.
- The googletest source code and libraries are not pushed to the repo anymore, they are fetched when the user runs cmake .... for the first time and are present for the subsequent runs unless deleted or changed.
- Deprecated googletest function calls have been replaced by the newer, supported function calls.