Provide callback for watch face to react to LCD state changes

[ljahn]

This provides a callback for watch faces to get notified about changes to the LCD state, meaning when it turns on and off or switches to and from the reduced color range of the Always On Display.

Example: My Star Trek watch face changes to different colors in AOD mode to enhance readability. It also has the option to animate the elements appearing when the watch face is opened.

This requires no changes to any watch face if the functionality is not used there, since it is a virtual void with an empty default implementation.

However, it adds an additional 100 tick delay on LCD sleep since lv_task_handler is not called in idle mode and we need time for one display refresh before entering idle. For AOD there is a similar thing with the display refresh rate decreasing, so updating before AOD is faster.

[github-actions[bot]]

Build size and comparison to main:

Section	Size	Difference
text	373280B	464B
data	948B	0B
bss	22536B	0B