UI: Add obs_frontend_open_source_interaction()

Adds a frontend api call to open the interact dialog of a source,
just like the `_properties` and `_filters` functions.

UI/window-basic-main.cpp

@@ -6199,6 +6199,15 @@ void OBSBasic::OpenProperties(OBSSource source)
 	CreatePropertiesWindow(source);
 }
 
+void OBSBasic::OpenInteraction(OBSSource source)
+{
+	if (source == nullptr) {
+		OBSSceneItem item = GetCurrentSceneItem();
+		source = obs_sceneitem_get_source(item);
+	}
+	CreateInteractionWindow(source);
+}
+
 void OBSBasic::OpenSceneFilters()
 {
 	OBSScene scene = GetCurrentScene();