On windows flags declaration must be prepend by `GTEST_API_`
to have the correct declspec (dllexport or dllimport)
This patch also fix super build integration of googletest by adding the necessary `INSTALL_RPATH` and `$<BUILD_INTERFACE:` needed to be able to `FetchContent` or `add_subdirectory()` googletest in a user CMake project.
Fix#4718
related to abseil/abseil-cpp#1817
PiperOrigin-RevId: 854187933
Change-Id: I4341fdb7e88a51c5f9a1c72c58bcc8c4d6bfd1c5