[lib] dispatch actions and populate aux user store with fids

Summary: Depends on D12105

Test Plan:
Hardcoded userIDs from staging as the user store and confirmed aux user store was populated with fids on connecting farcaster account

Diffed up first without a full end to end test. Will not land until I verify that the aux user store is properly populated with fids for users in the User Store

Reviewers: ginsu, ashoat

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D12011