hand seal to kuji-in

BUR #5818 has been approved by @Hillside_Moose.

create alias hand_seal -> kuji-in

Mostly for searchability, I could certainly move the 40 posts by hand.

Can't believe we actually had a separate tag. Yep, definitely needs to be aliased.

The bulk update request #5818 (forum #188214) has been approved by @Hillside_Moose.