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/common/logging/vst3.cpp

@@ -45,18 +45,18 @@ void Vst3Logger::log_request(bool is_host_vst,
     });
 }
 
+void Vst3Logger::log_request(bool is_host_vst,
+                             const YaPluginFactory::Construct&) {
+    log_request_base(is_host_vst,
+                     [](auto& message) { message << "GetPluginFactory()"; });
+}
+
 void Vst3Logger::log_request(bool is_host_vst, const WantsConfiguration&) {
     log_request_base(is_host_vst, [](auto& message) {
         message << "Requesting <Configuration>";
     });
 }
 
-void Vst3Logger::log_request(bool is_host_vst, const WantsPluginFactory&) {
-    log_request_base(is_host_vst, [](auto& message) {
-        message << "Requesting <IPluginFactory*>";
-    });
-}
-
 void Vst3Logger::log_response(bool is_host_vst, const Ack&) {
     log_response_base(is_host_vst, [&](auto& message) { message << "ACK"; });
 }
@@ -76,16 +76,15 @@ void Vst3Logger::log_response(
     });
 }
 
+void Vst3Logger::log_response(bool is_host_vst,
+                              const YaPluginFactory::ConstructArgs& args) {
+    log_response_base(is_host_vst, [&](auto& message) {
+        message << "<IPluginFactory*> with " << args.num_classes
+                << " registered classes";
+    });
+}
+
 void Vst3Logger::log_response(bool is_host_vst, const Configuration&) {
     log_response_base(is_host_vst,
                       [](auto& message) { message << "<Configuration"; });
 }
-
-void Vst3Logger::log_response(bool is_host_vst,
-                              const YaPluginFactory& factory) {
-    log_response_base(is_host_vst, [&](auto& message) {
-        message << "<IPluginFactory*> with "
-                << const_cast<YaPluginFactory&>(factory).countClasses()
-                << " registered classes";
-    });
-}