stub out secure as its own feature

quantum/process_keycode/process_secure.h

@@ -0,0 +1,9 @@
+// Copyright 2022 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <stdbool.h>
+#include "action.h"
+
+bool process_secure(uint16_t keycode, keyrecord_t *record);