[Driver] Add the --gcc-triple option (#73214)

When --gcc-triple is used, the driver will search for the 'best' gcc
installation that has the given triple. This is useful for distributions
that want clang to use a specific gcc triple, but do not want to pin to
a specific version as would be required by using --gcc-install-dir.
Having clang linked to a specific gcc version can cause clang to stop
working when the version of gcc installed on the system gets updated.