handwired/space_oddity: refactor, Configurator support and readme cleanup (#4977)

handwired/space_oddity: refactor, Configurator support and readme cleanup (#4977)

* handwired/space_oddity: refactor

- config.h: updated to use #pragma once include guard
- rules.mk: replace `?=` with `=`
- space_oddity.h:
  - updated to use #pragma once include guard
  - layout macro KEYMAP renamed to LAYOUT
- default keymap:
  - updated to use #include QMK_KEYBOARD_H
  - replace references to Planck keycodes
  - replace fn_actions-powered layer switch keycode
  - rebuild keymap block comments
  - keymap layers now use short-form keycodes
  - refactor action_get_macro keycodes into process_record_user

* handwired/space_oddity: Configurator support

* handwired/space_oddity: readme cleanup

- update readme to better conform with QMK template
- fixed the make command.