* Migrating `ACTION_LAYER_MOMENTARY()` entries in `fn_actions` to `MO()` keycodes
    * `fn_actions` is deprecated, and its functionality has been superseded by direct keycodes and `process_record_user()`
    * The end result of removing this obsolete feature should result in a decent reduction in firmware size and code complexity
    * All keymaps affected are recommended to switch away from `fn_actions` in favour of the [custom keycode](https://docs.qmk.fm/#/custom_quantum_functions) and [macro](https://docs.qmk.fm/#/feature_macros) features
