Normalized items

[brian-gates]

Problem: full copies of items exist everywhere. Reduce the size and redundancy of state by normalizing items within the character slice.

• [x] create items slice
• [x] create itemCreated action
• [x] dispatch itemCreated action whenever an item is added to the game
• [x] dispatch itemDestroyed action whenever an is removed from the game
• [ ] reduce statsModified in character slice on itemEquipped and itemRemoved (instead of within the selector)
• [ ] migrate character inventory and equipment to reference items slice
  • [ ] update selectors to denormalize back to original shape

Success criteria: No Items in the character slice, only ids. No change in behavior.

https://redux.js.org/usage/structuring-reducers/updating-normalized-data

Alternative for consideration: inventory slice.