Move GDScript uninitialization to GDScriptLanguage::finalize()

Co-authored-by: Ricardo Buring <ricardo.buring@gmail.com>
Co-authored-by: kleonc <9283098+kleonc@users.noreply.github.com>

modules/gdscript/gdscript_cache.h

@@ -111,6 +111,8 @@ public:
 		return singleton->destructing;
 	};
 
+	static void clear();
+
 	GDScriptCache();
 	~GDScriptCache();
 };