[protos][identity] Add RestoreUser RPCs

Summary:
Address ENG-8210.

Added RestorePasswordUser and RestoreWalletUser RPCs. These are described as "a single RPC" in the Whitepaper 5.2.
The API is very similiar to LogInPasswordUser[Start] / LogInWalletUser, with the additional device list payload. Also,
we're not doing OPAQUE login here for password users.

Test Plan: Flow, identity compiles.

Reviewers: ashoat, varun

Reviewed By: ashoat, varun

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13221