Add missing skip intro/credit to U-NEXT player
Add "Skip Intro" button just like you're on Netflix. Hotkey "S" also available.
Button will hide into playback control after 5 seconds from first displayed. Autoskip not available currently. May be implmented in future.
Implmentations are kinda tricky. If playback error/crashed/etc appears, disable this and try again.
*1. If button does not appeared for some episodes, means U-NEXT doesn't supports it since data are from site, not me.
*2. Whether "SKIP CREDITS" "NEXT EPISODE" will display are based on data from U-NEXT.
