feat(magic-items): add rarity to magic items (#455)

* feat(magic-items): add rarity and variants

Add rarity to magic items. If there are variants of an item and the rarity is different, the value
will be "Varies". Create variants, updating the text to match what the variant does

re #367

* fix(magic-items): fix description of tan bag of tricks

Co-authored-by: Chris Ward <cdurianward@gmail.com>

* feat(magic-items): add variant boolean

* feat(equipment-categories): add new variants

Co-authored-by: Chris Ward <cdurianward@gmail.com>

Author: Matt Loberg