[web] Add NeynarClientProvider on web

Summary:
We need this in order to be able to resolve FIDs to Farcaster usernames on web.

Depends on D11881

Test Plan: I tested resolution of Farcaster usernames in robotext on web

Reviewers: ginsu

Reviewed By: ginsu

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D11882