[Keymap] Added userspace for d4mation. Included their keymap for the Atreus62 (#7483)

* Added userspace for d4mation. Included their keymap for the Atreus62

* Do not assign layer numbers manually

* Remove some unneeded things per @drashna's recommendation

* Fix some single line comments I missed

* Update unicode macros to use send_unicode_hex_string() instead of process_unicode()

* OBetter check for Unicode Enabled. Moved some checks into macros.c

* Use eeconfig_init_user() to set default unicode input mode

users/d4mation/d4mation.c

@@ -0,0 +1,37 @@
+#include "d4mation.h"
+
+__attribute__ ((weak))
+bool process_record_keymap( uint16_t keycode, keyrecord_t *record ) {
+    /* If you want macros specific to your keymap, you need to define this function in your keymap */
+    return true;
+}
+
+__attribute__ ((weak))
+void matrix_init_keymap() {
+    /* If you want a matrix init specific to your keymap, you need to define this function in your keymap */
+}
+
+__attribute__ ((weak))
+void matrix_scan_keymap() {
+    /* If you want a matrix scan specific to your keymap, you need to define this function in your keymap */
+}
+
+__attribute__((weak))
+void eeconfig_init_keymap( void ) {}
+
+/* process_record_user() is called in macros.c */
+
+void matrix_init_user( void ) {
+    matrix_init_keymap();
+}
+
+void matrix_scan_user( void ) {
+    matrix_scan_keymap();
+}
+
+void eeconfig_init_user( void ) {
+
+    eeconfig_init_keymap();
+    keyboard_init();
+
+}