[identity] Replace usage of Device enum with DeviceType

Summary:
We can replace the usage of Device in database.rs and client_service.rs with the code generated DeviceType enum.
This reduces code duplication as we have implemented Display and TryFrom traits in shared.

Test Plan: Wrote basic unit tests utilizing try_from in database.rs and cargo builds

Reviewers: varun, jon

Reviewed By: varun

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D9474