Use the new approach for creating plugin factory

Directly serializing and deserializing into objects was and more
boilerplate heavy (since we now need two implementations even though we
only use one), and also much less flexible because we can't wrap
payloads in structs or provide optional values that way.

src/plugin/bridges/vst3-impls/plugin-factory.cpp

@@ -20,8 +20,10 @@
 
 #include "component.h"
 
-YaPluginFactoryPluginImpl::YaPluginFactoryPluginImpl(Vst3PluginBridge& bridge)
-    : bridge(bridge) {}
+YaPluginFactoryPluginImpl::YaPluginFactoryPluginImpl(
+    Vst3PluginBridge& bridge,
+    YaPluginFactory::ConstructArgs&& args)
+    : YaPluginFactory(std::move(args)), bridge(bridge) {}
 
 tresult PLUGIN_API
 YaPluginFactoryPluginImpl::createInstance(Steinberg::FIDString cid,

src/plugin/bridges/vst3-impls/plugin-factory.h

@@ -20,7 +20,8 @@
 
 class YaPluginFactoryPluginImpl : public YaPluginFactory {
    public:
-    YaPluginFactoryPluginImpl(Vst3PluginBridge& bridge);
+    YaPluginFactoryPluginImpl(Vst3PluginBridge& bridge,
+                              YaPluginFactory::ConstructArgs&& args);
 
     tresult PLUGIN_API createInstance(Steinberg::FIDString cid,
                                       Steinberg::FIDString _iid,

src/plugin/bridges/vst3.cpp

@@ -97,10 +97,12 @@ Steinberg::IPluginFactory* Vst3PluginBridge::get_plugin_factory() {
         // will request after loading the module. Host callback handlers should
         // have started before this since the Wine plugin host will request a
         // copy of the configuration during its initialization.
-        plugin_factory = new YaPluginFactoryPluginImpl(*this);
-        sockets.host_vst_control.receive_into(
-            WantsPluginFactory{}, *plugin_factory,
-            std::pair<Vst3Logger&, bool>(logger, true));
+        YaPluginFactory::ConstructArgs factory_args =
+            sockets.host_vst_control.send_message(
+                YaPluginFactory::Construct{},
+                std::pair<Vst3Logger&, bool>(logger, true));
+        plugin_factory =
+            new YaPluginFactoryPluginImpl(*this, std::move(factory_args));
     }
 
     return plugin_factory;