This gives some flexibility to embedders.
Currently, embedders have to build a binary for each test file.
After this CL, embedders can still choose to have a binary for each test
file, by linking each test file with a googletest target that includes
main() (usually "gtest_main"). Embedders can also choose to build a
single binary for almost all test files, and link with a googletest
target that includes main(). The latter is more convenient for projects
that have very few test binaries, like Chromium.
PiperOrigin-RevId: 419470798
8f464e7f68