[Feature] Add image categorization about stash-box

[echo6ix]

This is related to #237

This is a good and necessary feature.

• Might be simplest to implement these like tags
• Do we provide a fixed set of tags that are controlled by admin, or do we allow users to create tags?

Image metadata like resolution doesn't need tags since it can be derived without user input, but should still definitely be presented

• Resolution
• File size
• Username (of uploader)
• Date submitted

We could use this metadata and tags to decide how we display performer images on StashDB and potentially what Stash scrapes from stashbox.

• Which performer images to display in dropdown query boxes? Prioritize ones with a headshot tag (because it's easier to identify a performer from a headshot when the image is a thumbnail)
• User's scraping the stashbox and wants consistent performer images?
  • User can specify to prioritize a headshot or body shot or whatever tag.
  • User can specify to prioritize a particular tag from a particular username etc. These could be potential possibilities