Implement IPluginFactory3::setHostContext()

Now the plugin factories are fully implemented (at least, functionality
wise, we still can't create most kinds of objects).

src/wine-host/bridges/vst2.cpp

@@ -100,7 +100,7 @@ Vst2Bridge::Vst2Bridge(MainContext& main_context,
     sockets.connect();
 
     // Initialize after communication has been set up
-    // We'll try to do the same `get_bridge_isntance` trick as in
+    // We'll try to do the same `get_bridge_instance` trick as in
     // `plugin/plugin.cpp`, but since the plugin will probably call the host
     // callback while it's initializing we sadly have to use a global here.
     {

src/wine-host/bridges/vst3.cpp

@@ -111,6 +111,19 @@ void Vst3Bridge::run() {
                 -> YaPluginFactory::Construct::Response {
                 return YaPluginFactory::ConstructArgs(
                     module->getFactory().get());
+            },
+            [&](YaPluginFactory::SetHostContext& request)
+                -> YaPluginFactory::SetHostContext::Response {
+                plugin_factory_host_application_context =
+                    Steinberg::owned(new YaHostApplicationHostImpl(
+                        *this,
+                        std::move(request.host_application_context_args)));
+
+                Steinberg::FUnknownPtr<Steinberg::IPluginFactory3> factory_3(
+                    module->getFactory().get());
+                assert(factory_3);
+                return factory_3->setHostContext(
+                    plugin_factory_host_application_context);
             }});
 }
 

src/wine-host/bridges/vst3.h

@@ -99,6 +99,13 @@ class Vst3Bridge : public HostBridge {
      */
     std::atomic_size_t current_instance_id;
 
+    /**
+     * The host application context proxy object if we got passed a host
+     * application context during a call to `IPluginFactory3::setHostContext()`
+     * by the host.
+     */
+    Steinberg::IPtr<YaHostApplication> plugin_factory_host_application_context;
+
     // Below are managed instances we created for
     // `IPluginFactory::createInstance()`. The keys in all of these maps are the
     // unique identifiers we generated for them so we can identify specific