Move proto definitions to separate repo

[TarikViehmann]

Having a separate repo for proto messages allows all communicators (refbox, simulations, team servers, robots) to integrate that repo as a submodule.

[pkohout]

@TarikViehmann if you create an empty repository I would be up to move the proto messages there and setup up a GitHub action that builds a deb file, so that teams can simply install them via apt.

[pkohout]

I tested our dockerfile for the webshop we used back in the day, this is not building anymore because the clips-rest-api does not build. I guess since the webshop will only need the refbox messages we could get rid of it once we move them to an empty repo.

      --> Entering sub-directory rest-api ---
         --- Compiling webview_server.cpp (C++)
         --- Compiling service_browse_handler.cpp (C++)
         --- Compiling rest_processor.cpp (C++)
         --- Compiling clips-rest-api/clips-rest-api.cpp (C++)
         --- Compiling clips-rest-api/model/Fact.cpp (C++)
         --- Compiling clips-rest-api/model/SlotValue.cpp (C++)
         --- Compiling clips-rest-api/model/RingSpec.cpp (C++)
         --- Compiling clips-rest-api/model/Robot.cpp (C++)
/root/rcll-refbox/src/libs/rest-api/clips-rest-api/clips-rest-api.cpp: In member function ‘Fact llsfrb::ClipsRestApi::gen_fact(CLIPS::Fact::pointer&, bool)’:
/root/rcll-refbox/src/libs/rest-api/clips-rest-api/clips-rest-api.cpp:179:96: error: ISO C++ forbids converting a string constant to ‘char*’ [-Werror=write-strings]
   PrintFact(env_->cobj(), (const char *)"ProcPPForm", (struct fact *)fact->cobj(), FALSE, FALSE);
                                                                                                ^
         --- Compiling clips-rest-api/model/Environment.cpp (C++)
         === Linking lib libllsf_protobuf_clips ---
         --- Compiling clips-rest-api/model/Points.cpp (C++)
         <-- Leaving protobuf_clips
         --- Compiling clips-rest-api/model/GameState.cpp (C++)
         --- Compiling clips-rest-api/model/Order.cpp (C++)