[native_rust_library] reserved registration client methods for wallet and password users

Summary: we need these client methods to call the reserved registration RPCs if login fails because the user exists on ashoat's keyserver but is not yet registered on identity

Test Plan: tested from js later in stack by calling the useLogIn hook with a reserved username and reserved wallet address and confirming that i was registered on identity

Reviewers: bartek, will

Reviewed By: bartek

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11908