Tries to make the given slasher jumpscare and kill a target survivor.
Fails silently if the slasher can't currently kill, is on kill delay, the target isn't a valid survivor, or the target is out of the slasher's SLASHER.KillDistance (unless they're already being jumpscared).
On success it freezes both entities, plays the slasher's kill sound, and after SLASHER.JumpscareDuration seconds deals fatal damage to the target and calls the slasher's SLASHER.OnKillPlayer function via Player:SlasherFunction.