[lib] Factor out Wagmi configuration logic into lib

Summary:
Note that there's a downside here, which is adding wagmi to lib which might eg. bloat native bundle size inadvertently

But also native bundle size is the least important bundle size

Test Plan: I made sure both the mobile (landing) and web workflows still worked

Reviewers: atul

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D6371