[1.1] Create /catalog endpoint

[flobarreto]

Nowadays we’ve two requests to get assets, the one that picks items and the one that picks nfts.

We need to have one new request (get) that brings all items paired with the nfts for this items

We’ll want to conserve the current endpoints for items (/items) and NFTs (/nfts) so we don’t introduce breaking changes for third parties consuming them. Having said that, we still need a new way to consume the grouped data. We’ll need a new endpoint that retrieves the data needed to create the “catalog” for the listing pages.

Create an endpoint /catalog that returns the data needed for rendering the unified cards. Let’s call those object listings. At the same time, it should support all of the current filters.
- Data needed in the response:
- Item fields:
- name
- creator
- minting info
- available (to show stock)
- price for minting
- listings info
- how many listings there are
- price range (low to max)
- rarity
- category
- body shape
- Supported status filters:
- Available for sale
- available > 0
- order > 0
- only available for minting
- available > 0
- order = null
- only listings
- available = 0
- order > 0
- not for sale
- available = 0
- order = null