TrSmoothFadeX<MILLIS_FUNCTION> TrSmoothFade<MILLIS>
Similar to TrFade, but uses a cubic fading function so fading starts slow, speeds up in the middle, then slows down at the end.
TrFadeX
https://github.com/profezzorn/ProffieOS/blob/6f8add544c627172ad2dd698c90e5e55078a420a/transitions/fade.h#L29