Extend asset endpoints to expose "manifests"

[donaldgray]

The new "manifests" property needs to be added to Hydra Image class and mapped from DB entity and returned for any read/write endpoints.

{
  "@context": "https://api.dlcs.digirati.io/contexts/Image.jsonld",
  "@id": "https://api.dlcs/customers/2/spaces/1/images/first",
  "@type": "vocab:Image",
  "id": "first",
  "manifests": ["m123", "aadopsi0"]
}

This property should be rendered, if set, everywhere the Hydra image class can be returned:

• GET|PATCH /customers/{c}/spaces/{s}/images
• POST /customers/{c}/allImages
• GET|PUT|PATCH /customers/{c}/spaces/{s}/images/{i}
• GET /customers/{c}/queue/batches/{b}/images
• GET /customers/{c}/queue/batches/{b}/assets
• POST /customesr/{c}/queue
• POST /customesr/{c}/queue/priority
• verify that the above is the comprehensive list of endpoints, add any that have been missed

For updates, "manifests" can be:

• An array with values (e.g. ["foo", "bar"]) - this will replace any currently saved values
• null - this will save null if new asset, or leave any existing "manifests" if update
• [] - this is explicitly clearing the values, so null in database.