[native_rust_library] implement link_farcaster_account client method

Summary:
client method which calls the LinkFarcasterAccount RPC. this is an auth RPC so we need the userID, deviceID, and CSAT

Depends on D11406

Test Plan: Later in the stack we call this rust client method from JS and successfully add a farcasterID to an existing user

Reviewers: bartek

Reviewed By: bartek

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11407