Log a warning when encountering unknown interfaces

src/plugin/bridges/vst3.h

@@ -63,6 +63,12 @@ class Vst3PluginBridge : PluginBridge<Vst3Sockets<std::jthread>> {
      */
     Steinberg::IPluginFactory* get_plugin_factory();
 
+    /**
+     * The logging facility used for this instance of yabridge. Wraps around
+     * `PluginBridge::generic_logger`.
+     */
+    Vst3Logger logger;
+
    private:
     /**
      * Handles callbacks from the plugin to the host over the
@@ -70,12 +76,6 @@ class Vst3PluginBridge : PluginBridge<Vst3Sockets<std::jthread>> {
      */
     std::jthread host_callback_handler;
 
-    /**
-     * The logging facility used for this instance of yabridge. Wraps around
-     * `PluginBridge::generic_logger`.
-     */
-    Vst3Logger logger;
-
     /**
      * Our plugin factory. All information about the plugin and its supported
      * classes are copied directly from the Windows VST3 plugin's factory on the