Feature: Item, ItemType, ItemRariy, ItemQuality classes

We need an entity for items, item types, and a valueobject enum for the quality.

# Entity/Item
- ItemId Id
- ItemTypeId TypeId
- ItemType Type
- ItemQuality Quality
- UserId OwnerId
- User Owner

# Entity/ItemType
- ItemTypeId Id
- string Name
- string? Description
- float QualityMin // the minimum quality this item appears in
- float QualityMax // the maximum quality this item can have
- bool StatTrackAvailable // whether or not stat track is available
- string ImageUrl
## methods
// creates a new item, who belongs to the user specified.
// the rarity and the quality are randomly generated.
// only 25% of items are stat track
- Item NewItem(User owner);

# ValueObject/ItemQuality
- float Value
- bool IsStatTrack