Add Sinc keyboard (#8986)

* Add Sinc (WIP)

* Rename layouts, add keymaps

* Set EEPROM VIA layout value

* Update QMK Configurator json

* Update VIA layout value

* Add default folder

* Add PR suggestions

* Fix keyboard name

keyboards/keebio/sinc/sinc.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include "quantum.h"
+
+#ifdef KEYBOARD_keebio_sinc_rev1
+    #include "rev1.h"
+#endif