Add STATIC_CALLED_ON_INSTANCE warning to highlight

when static functions are called directly from objects

modules/gdscript/gdscript_warning.h

@@ -78,6 +78,7 @@ public:
 		EMPTY_FILE, // A script file is empty.
 		SHADOWED_GLOBAL_IDENTIFIER, // A global class or function has the same name as variable.
 		INT_ASSIGNED_TO_ENUM, // An integer value was assigned to an enum-typed variable without casting.
+		STATIC_CALLED_ON_INSTANCE, // A static method was called on an instance of a class instead of on the class itself.
 		WARNING_MAX,
 	};