Remove 'locale' parameter from all callbacks

The locale parameter was a mistake, because it puts extra needless
burden upon the module developer to have to handle this variable for
each and every single callback function.  The parameter is being removed
in favor of a single centralized module callback function that
specifically updates locale information for a module only when needed.

libobs/obs-scene.c

@@ -43,10 +43,9 @@ static inline void signal_item_remove(struct obs_scene_item *item)
 	calldata_free(&params);
 }
 
-static const char *scene_getname(const char *locale)
+static const char *scene_getname(void)
 {
 	/* TODO: locale */
-	UNUSED_PARAMETER(locale);
 	return "Scene";
 }