Syncing items on sheets from compendium

[AndroidSalmon]

Currently, items added to sheets are copies of the original which don't update when the original in the compendium does. This makes sense for many things. When using items as powers/gifts/etc. that should be universally the same, it'd be nice to have the option to update copies on a sheet based on the original in one go (for example, to fix a typo, DC, etc)

https://github.com/JohanFalt/Foundry_WoD20/issues/466