[Keyboard] Add DGG-56 Handwired (#8740)

* Add ddg_56 keyboard

* Add ddg_56 default keymap

* Fix config.h

* Update config.h

* Update ddg_56.h

* Update keyboards/handwired/ddg_56/readme.md

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

* Update keyboards/handwired/ddg_56/readme.md

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

* Update keyboards/handwired/ddg_56/info.json

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

Co-authored-by: Ryan <fauxpark@gmail.com>
Co-authored-by: Joel Challis <git@zvecr.com>

keyboards/handwired/ddg_56/rules.mk

@@ -0,0 +1,17 @@
+# MCU name
+MCU = STM32F303
+
+# Build Options
+#   change to "no" to disable the options, or define them in the Makefile in
+#   the appropriate keymap folder that will get included automatically
+#
+BOOTMAGIC_ENABLE = yes      # Virtual DIP switch configuration
+MOUSEKEY_ENABLE = no      # Mouse keys
+EXTRAKEY_ENABLE = no       # Audio control and System control
+CONSOLE_ENABLE = no         # Console for debug
+COMMAND_ENABLE = no       # Commands for debug and configuration
+NKRO_ENABLE = yes            # Nkey Rollover - if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work
+BACKLIGHT_ENABLE = no      # Enable keyboard backlight functionality
+MIDI_ENABLE = no            # MIDI controls
+AUDIO_ENABLE = yes           # Audio output on port C6
+UNICODE_ENABLE = no         # Unicode