[Fate] Random aliases/renames

Posted under Tags

The bulk update request #9350 has been approved by @evazion.

rename lancer_(prisma_illya) -> cu_chulainn_(prisma_illya)
rename saber_venus -> nero_claudius_(saber_venus)_(fate)
create alias piercing_bunny -> char:scathach_(piercing_bunny)_(fate)
create implication scathach_(piercing_bunny)_(fate) -> scathach_(fate)

Just some random tags that needed cleaning.

For lancer_(prisma_illya) -> cu_chulainn_(prisma_illya), it's the same naming format as for other characters from Prisma Illya, so there's no *_(fate) qualifier at the end. I manually changed rider (prisma illya) to medusa (prisma illya), so it's just Cu who could use the rename.

For saber_venus -> nero_claudius_(saber_venus)_(fate), it's to move away from class names for Servants as much as possible.

For the Piercing Bunny requests, it's just moving from a costume gentag to a chartag like what's being done in topic #20741.

Those were the 'weird' tags that I felt needed gardening, but I didn't want to do them manually.