[lib] useIdentityWalletRegister hook

Summary:
hook for wallet registration that will be used in siwe-hooks.js in D11005

Depends on D11083

Test Plan: for now, i've only tested this code by running flow. this will be tested more thoroughly in the subsequent diffs that use the hook

Reviewers: ashoat, inka, tomek

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D11084