Refactor plugin factories into Vst3*Proxy format

Now every proxy object that's directly created by the host or plugin
shares the same structure.

src/common/serialization/vst3/plugin-factory-proxy.cpp

@@ -0,0 +1,58 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020-2021 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "plugin-factory-proxy.h"
+
+Vst3PluginFactoryProxy::ConstructArgs::ConstructArgs() {}
+
+Vst3PluginFactoryProxy::ConstructArgs::ConstructArgs(
+    Steinberg::IPtr<Steinberg::FUnknown> object)
+    : plugin_factory_args(object) {}
+
+Vst3PluginFactoryProxy::Vst3PluginFactoryProxy(const ConstructArgs&& args)
+    : YaPluginFactory3(std::move(args.plugin_factory_args)),
+      arguments(std::move(args)){FUNKNOWN_CTOR}
+
+      // clang-format just doesn't understand these macros, I guess
+      Vst3PluginFactoryProxy::~Vst3PluginFactoryProxy() {
+    FUNKNOWN_DTOR
+}
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdelete-non-virtual-dtor"
+IMPLEMENT_REFCOUNT(Vst3PluginFactoryProxy)
+#pragma GCC diagnostic pop
+
+tresult PLUGIN_API
+Vst3PluginFactoryProxy::queryInterface(Steinberg::FIDString _iid, void** obj) {
+    if (YaPluginFactory3::supports_plugin_factory()) {
+        QUERY_INTERFACE(_iid, obj, Steinberg::FUnknown::iid,
+                        Steinberg::IPluginFactory)
+        QUERY_INTERFACE(_iid, obj, Steinberg::IPluginFactory::iid,
+                        Steinberg::IPluginFactory)
+    }
+    if (YaPluginFactory3::supports_plugin_factory_2()) {
+        QUERY_INTERFACE(_iid, obj, Steinberg::IPluginFactory2::iid,
+                        Steinberg::IPluginFactory2)
+    }
+    if (YaPluginFactory3::supports_plugin_factory_3()) {
+        QUERY_INTERFACE(_iid, obj, Steinberg::IPluginFactory3::iid,
+                        Steinberg::IPluginFactory3)
+    }
+
+    *obj = nullptr;
+    return Steinberg::kNoInterface;
+}