Expanded handler implementation, more key defines.

src/handlers.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include "keymap.h"
+#include <dt-bindings/zmk/keys.h>
+
+struct zmk_key_event
+{
+    zmk_key key;
+    bool pressed;
+};
+
+void zmk_handle_key(struct zmk_key_event key_event);