split up unicode systems into different files

quantum/process_keycode/process_unicodemap.h

@@ -0,0 +1,8 @@
+#ifndef PROCESS_UNICODEMAP_H
+#define PROCESS_UNICODEMAP_H
+
+#include "quantum.h"
+
+void unicode_map_input_error(void);
+bool process_unicode_map(uint16_t keycode, keyrecord_t *record);
+#endif