Bundle associated messages with their interfaces

Once we start implementing all of the control messages/callbacks things
could quickly get out of hand otherwise.

src/common/serialization/vst3.h

@@ -38,20 +38,8 @@
 // TODO: If this approach works, maybe we can also refactor the VST2 handling to
 //       do this since it's a bit safer and easier to read
 
-/**
- * Request the Wine plugin host to instantiate a new IComponent to pass through
- * a call to `IPluginFactory::createInstance(cid, IComponent::iid, ...)`.
- */
-struct CreateInstaneIComponent {
-    using Response = YaComponent&;
-
-    Steinberg::TUID cid;
-
-    template <typename S>
-    void serialize(S& s) {
-        s.container1b(cid);
-    }
-};
+// All messages for creating objects and calling interfaces on them are defined
+// as part of the interfaces and implementations in `vst3/`
 
 /**
  * Marker struct to indicate the other side (the plugin) should send a copy of
@@ -80,8 +68,7 @@ struct WantsPluginFactory {
  * encodes the information we request or the operation we want to perform. A
  * request of type `ControlRequest(T)` should send back a `T::Response`.
  */
-using ControlRequest =
-    std::variant<CreateInstaneIComponent, WantsPluginFactory>;
+using ControlRequest = std::variant<YaComponent::Create, WantsPluginFactory>;
 
 template <typename S>
 void serialize(S& s, ControlRequest& payload) {