Add required set of attributes for items on wishlists

[Encotric]

As a group member, I want to be forced to specify at least the following attributes for an item when adding a wish to a group's wishlist:

book:

• name
• author

movie:

• name
• release date
• director

game:

• name
• publisher

other:

• name
• category

Dependencies

Depends on:

• Add group wishlists #232

Acceptance Criteria

• group members face a human-readable error when not specifying the minimum attributes for new wishlist items