[Keyboard] Add Meck TKL handwired (#15533)

* Add meck_tkl

* Fix configuration and pin assignment

* Rellocate A10 pin, as it is used by the USB DFU bootloader

* Add volume and media keys to the function keys layer

* Rellocate source files to the handwired keyboards folder and add documentation

* Review changes for PR
- Improve LAYOUT macro to match the keyboard layout.
- Use "kxy" as pin names on the LAYOUT macro.
- Remove unused mcuconf.h and halconf.h.
- Fix README.

* Improve layout macro naming

keyboards/handwired/meck_tkl/config.h

@@ -0,0 +1,47 @@
+// Copyright 2021 Gabriel Kim (@gabrielkim13)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "config_common.h"
+
+/* USB Device descriptor parameter */
+#define VENDOR_ID    0x474B
+#define PRODUCT_ID   0x0001
+#define DEVICE_VER   0x0001
+#define MANUFACTURER gabrielkim13
+#define PRODUCT      Meck TKL
+
+/* key matrix size */
+#define MATRIX_ROWS 6
+#define MATRIX_COLS 17
+
+/*
+ * Keyboard Matrix Assignments
+ *
+ * Change this to how you wired your keyboard
+ * COLS: AVR pins used for columns, left to right
+ * ROWS: AVR pins used for rows, top to bottom
+ * DIODE_DIRECTION: COL2ROW = COL = Anode (+), ROW = Cathode (-, marked on diode)
+ *                  ROW2COL = ROW = Anode (+), COL = Cathode (-, marked on diode)
+ *
+ */
+
+/* COL2ROW, ROW2COL */
+#define DIODE_DIRECTION COL2ROW
+
+/* Debounce reduces chatter (unintended double-presses) - set 0 if debouncing is not needed */
+#define DEBOUNCE 5
+
+/* Mechanical locking support. Use KC_LCAP, KC_LNUM or KC_LSCR instead in keymap */
+#define LOCKING_SUPPORT_ENABLE
+/* Locking resynchronize hack */
+#define LOCKING_RESYNC_ENABLE
+
+/* disable these deprecated features by default */
+#define NO_ACTION_MACRO
+#define NO_ACTION_FUNCTION
+
+/* Bootmagic Lite key configuration */
+//#define BOOTMAGIC_LITE_ROW 0
+//#define BOOTMAGIC_LITE_COLUMN 0