Tagging and Data Overlays

## Problem Statement

There are times when the community would like to attach additional information to claims. Some examples:

- grouping content into collections (e.g. "anime", "subtitled films", "babies playing with puppies", "ama", "intro-level lectures", etc)
- some collections may be permissioned (e.g. grin's workout playlist)
- warning others that a file may contain a virus or other malware
- marking content as nsfw when the original publisher did not do so
- changing inaccurate information in the claim (updating filetype, fixing typo, changing language or description, etc)

This problem can be generalized into the (admittedly ill-defined) questions of:
- How do we allow attachment of binary attributes to URLs in a community controlled or influenced manner?
- Can and should this solution be generalized to allow similar control of non-binary attributes (e.g. a description)?

## Requirements

- useful to content consumers
- on-chain (probably)
- decentralized (lbry inc has no special privileges)
- performant
- some community edits will be contentious. how does the system deal with that?
- the original publisher should probably have some special authority to manage edits, but should not have unilateral control over them
- ... or maybe not?

## Owner

TBD (Jeremy for now)

No files, tests, or implementation entry points are named. Start by reviewing the problem statement and requirements, then clarify the proposed on-chain model, permissions, contentious edits, and performance expectations with the project maintainers. Done would require an agreed design and an identified implementation scope.

Written by the indexing model from the issue text.