[Keyboard] Added D48 keyboard (#8548)

* [Keyboard] Added D48 keyboard.

* Updated README.

* Cleanups.

* Moved d48 to handwired/

* Added link to build process album.

* Coding conventions cleanups.

* Added DS1307 RTC!

* Minor cleanups.

* Apply suggestions from code review

Co-Authored-By: Drashna Jaelre <drashna@live.com>

* Minor refactoring.

* Readme fix.

* Moved leftover keymap-specific code from keyboard space into keymap.

* Added encoder button pins to extra matrix row.

* Updated README, updated pinout & cleaned up the glcdfont

* Apply suggestions from code review

Co-Authored-By: Drashna Jaelre <drashna@live.com>

* Update config.h

* Apply suggestions from code review

Co-Authored-By: Ryan <fauxpark@gmail.com>

* Added default keymap. Refactored existing keymap.

* Update keyboards/handwired/d48/README.md

Co-Authored-By: Ryan <fauxpark@gmail.com>

* Apply suggestions from code review

Co-Authored-By: Joel Challis <git@zvecr.com>

* Minor alignment fix.

* Update keyboards/handwired/d48/glcdfont_d48.c

Co-Authored-By: Ryan <fauxpark@gmail.com>

* Changes as per PR.

* Apply suggestions from code review

Co-authored-by: James Young <18669334+noroadsleft@users.noreply.github.com>

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: Ryan <fauxpark@gmail.com>
Co-authored-by: Joel Challis <git@zvecr.com>
Co-authored-by: James Young <18669334+noroadsleft@users.noreply.github.com>

users/anderson/seq.h

@@ -0,0 +1,14 @@
+#include "quantum.h"
+
+#include <string.h>
+
+typedef struct seq_t {
+    const char *sequence;
+    const char *result;
+} seq_t;
+
+extern seq_t seq_config[];
+extern uint16_t seq_config_size;
+
+void seq_start(void);
+bool seq_feed(uint16_t keycode);