[lib][native][web] Add Farcaster users to EntityText framework
Summary:
We want to be able to specify Farcaster users based on FIDs in EntityText, so that we can resolve them to their usernames in robotext and notifs.
Depends on D11878
Test Plan:
I tested this in combination with later diffs on both keyserver and web:
- For keyserver, I tested that Farcaster usernames worked in notifs
- For web, I tested that Farcaster usernames were resolved in robotext
Reviewers: ginsu
Reviewed By: ginsu
Subscribers: tomek
Differential Revision: https://phab.comm.dev/D11879