Add function to allow repeated blinking of one layer (#12237)
* Implement function rgblight_blink_layer_repeat to allow repeated blinking of one layer at a time
* Update doc
* Rework rgblight blinking according to requested change
* optimize storage
would turn the layer 0 (or 1) on and off again three times when `DEBUG` is pressed.
### Overriding RGB Lighting on/off status
Normally lighting layers are not shown when RGB Lighting is disabled (e.g. with `RGB_TOG` keycode). If you would like lighting layers to work even when the RGB Lighting is otherwise off, add `#define RGBLIGHT_LAYERS_OVERRIDE_RGB_OFF` to your `config.h`.