Also make the GroupHost plugin type agnostic

src/wine-host/bridges/common.h

@@ -24,6 +24,9 @@
  * will actually host a plugin and do all the function call forwarding.
  */
 class HostBridge {
+   protected:
+    HostBridge(boost::filesystem::path plugin_path);
+
    public:
     virtual ~HostBridge(){};
 
@@ -64,6 +67,11 @@ class HostBridge {
      */
     void handle_win32_events();
 
+    /**
+     * The path to the .dll being loaded in the Wine plugin host.
+     */
+    const boost::filesystem::path plugin_path;
+
    protected:
     /**
      * The plugin editor window. Allows embedding the plugin's editor into a