[lib] Introduce NeynarClient.getFarcasterUsernames and FCCache
Summary:
FCCache is modeled after ENSCache, as it serves a similar purpose: caching the results of lookups.
Depends on D11875
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/D11876