Fully implement IComponentHandler2

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

@@ -360,6 +360,7 @@ tresult PLUGIN_API Vst3PluginProxyImpl::setComponentHandler(
 
         // Automatically converted smart pointers for when the plugin performs a
         // callback later
+        component_handler_2 = component_handler;
         unit_handler = component_handler;
 
         return bridge.send_message(YaEditController::SetComponentHandler{

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

@@ -244,6 +244,8 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
     // The following pointers are cast from `component_handler` if
     // `IEditController::setComponentHandler()` has been called
 
+    Steinberg::FUnknownPtr<Steinberg::Vst::IComponentHandler2>
+        component_handler_2;
     Steinberg::FUnknownPtr<Steinberg::Vst::IUnitHandler> unit_handler;
 
    private: