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/wine-host/bridges/vst3.cpp

@@ -17,7 +17,6 @@
 #include "vst3.h"
 
 #include "../boost-fix.h"
-#include "vst3-impls.h"
 
 #include <public.sdk/source/vst/hosting/module_win32.cpp>
 
@@ -36,11 +35,6 @@ Vst3Bridge::Vst3Bridge(MainContext& main_context,
 
     sockets.connect();
 
-    // Serialize the plugin's plugin factory. The native VST3 plugin will
-    // request a copy of this during its initialization.
-    plugin_factory =
-        std::make_unique<YaPluginFactoryHostImpl>(module->getFactory().get());
-
     // Fetch this instance's configuration from the plugin to finish the setup
     // process
     config = sockets.vst_host_callback.send_message(WantsConfiguration{},
@@ -82,8 +76,10 @@ void Vst3Bridge::run() {
                 -> YaComponent::Terminate::Response {
                 return component_instances[request.instance_id]->terminate();
             },
-            [&](const WantsPluginFactory&) -> WantsPluginFactory::Response {
-                return *plugin_factory;
+            [&](const YaPluginFactory::Construct&)
+                -> YaPluginFactory::Construct::Response {
+                return YaPluginFactory::ConstructArgs(
+                    module->getFactory().get());
             }});
 }