Entities: Add "tags" to properties for all entities.

[digisomni]

Current user data is heavy, it requires parsing and unparsing(?) JSON every time, it's not JSON by default, and it requires reading and editing the entire property every time instead of a select few parts.

The tags property will be a JSON list and individual tags will be readable and editable through APIs on the client end.

[stale]

Hello! Is this still an issue?