WIP: GraphQL bindings with protobuffer annotations

[emcfarlane]

Bind services to graphql methods with protobuf annotations.

message Faction {
  string name = 1;
  string display_name = 2;
  option (larking.api.edge) = {
    name : "ships"
    method : "/larking.api.StarWars/ListShips"
  };
}

service StarWars {
   rpc GetFaction(GetFactionRequest) returns (Faction) {
     option (larking.api.graphql) = {
       query : "faction"
     };
  }
}