Add onekey keymap for testing reset to bootloader. (#8288)

keyboards/handwired/onekey/keymaps/reset/keymap.c

@@ -0,0 +1,5 @@
+#include QMK_KEYBOARD_H
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+  LAYOUT( RESET )
+};