libprotobuf is a very annoying dependency to deal with, and with the switch to nanopb for generated C++ code, libprotobuf is only used for dynamic decode in the GUI apps. libprotobuf has been swapped out with upb, a much smaller C-based library that supports reflection and can therefore do dynamic decode. This means we can remove the libprotobuf dependency and stop dealing with build issues because of it.
- Add builtin registry baseline (fixes building locally with msvc builtin vcpkg)
- Add protobuf as an explicit dependency (previously was installed as a dependency of opencv)
- In windows CI, checkout repository before running vcpkg (silences warning that vcpkg.json was not found)
