[lib/native] introduce useLinkFID hook

Summary:
This diff introduces useLinkFID which is a hook that returns a callback that calls the linkFarcasterAccount identity rpc and then sets the fid into the synced metadata client store

Depends on D11873

Test Plan:
Confirmed that the fid was being set into the synced metadata client store + confirmed in meeting with @varun that I was correctly calling and getting the expected behavior of linkFarcasterAccount RPC.

Confirmed that loading + error states worked as expected

Reviewers: will, varun, ashoat

Reviewed By: ashoat

Subscribers: ashoat, tomek, varun

Differential Revision: https://phab.comm.dev/D11863