[Keyboard] Add Snatchpad keyboard (#16330)

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: Ryan <fauxpark@gmail.com>
Co-authored-by: xia0 <xiao@morgan.net.au>

keyboards/handwired/snatchpad/snatchpad.h

@@ -0,0 +1,24 @@
+// Copyright 2022 xia0 (@xia0)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "quantum.h"
+
+/* This is a shortcut to help you visually see your layout.
+ *
+ * The first section contains all of the arguments representing the physical
+ * layout of the board and position of the keys.
+ *
+ * The second converts the arguments into a two-dimensional array which
+ * represents the switch matrix.
+ */
+#define LAYOUT( \
+    k00, k01, k02, \
+    k10, k11, k12, \
+    k20,      k22  \
+) { \
+    { k00    , k01    , k02 }, \
+    { k10    , k11    , k12 }, \
+    { k20    , KC_NO  , k22 }  \
+}