https://gitlab.kitware.com/cmake/cmake/issues/19875#note_705896 it is
possible to FetchContent protobuf. Is it feasible to use that protobuf
and it’s compiler for the protobuf_generate_cpp and
protobuf_generate_python functions of FindProtobuf?
Those functions expect a protobuf compiler for compilation, but the
compiler will only be available after the targets introduced by
FetchContent have finished compilation.