[Keyboard] XD75 refactor (#5420)

* Refactor layout macro names

Update the names of the layout macros to reflect QMK's desired usage.

- KEYMAP renamed to LAYOUT
  - colinta keymap updated accordingly
- KC_KEYMAP renamed to LAYOUT_kc
  - mtdjr keymap updated accordingly

* Update xd75.h to use #pragma once include guard

* Update keymaps to use QMK_KEYBOARD_H

* Refactor default keymap

- updated to use layout macro
- remove deprecated action_get_macro function
- add functions from QMK keymap.c template
  - process_record_user
  - matrix_init_user
  - matrix_scan_user
  - led_set_user

* Update supporting files

- updated config.h files to use #pragma once include guard
- remove errant QUANTUM_DIR code block

* Rename readme files to fully lowercase filenames

* Restructure keyboard readme

Updated the readme to better align with the current QMK template.

* Bugfixes to supporting files

keyboards/xd75/keymaps/mtdjr/keymap.c

@@ -3,7 +3,7 @@
 
 const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
 
- [_QWERTY] = KC_KEYMAP(
+ [_QWERTY] = LAYOUT_kc(
 //  .--------------------------------------------------------------------------.
       EXC, 1  , 2  , 3  , 4  , 5  ,PGUP,MPNT,PGDN, 6  , 7  , 8  , 9  , 0  ,BSPC,
 //  |----+----+----+----+----+----+----+----+----+----+----+----+----+----+----|
@@ -17,7 +17,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
 //  '----+----+----+----+----+----+----+----+----+----+----+----+----+----+----'
 ),
 
- [_LOWER] = KC_KEYMAP(
+ [_LOWER] = LAYOUT_kc(
 //  .--------------------------------------------------------------------------.
      xxxx, F1 , F2 , F3 , F4 , F5 , F6 ,xxxx, F7 , F8 , F9 , F10, F11, F12, DEL,
 //  |----+----+----+----+----+----+----+----+----+----+----+----+----+----+----|
@@ -31,7 +31,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
 //  '----+----+----+----+----+----+----+----+----+----+----+----+----+----+----'
 ),
 
-[_RAISE] = KC_KEYMAP(
+[_RAISE] = LAYOUT_kc(
 //  .--------------------------------------------------------------------------.
      xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,xxxx,
 //  |----+----+----+----+----+----+----+----+----+----+----+----+----+----+----|