Add support for voice registration

[Export33]

The signal-cli supports voice registration for landline numbers. Can you add the --voice command?

When i register myself in the shell
docker exec -it signal-cli-rest-api sh
signal-cli -u +49xxxxxx register --voice

i get an authorization error during the verification using the rest service:
{"error":"Authorization failed, was the number registered elsewhere?\nError loading state file: Authorization failed!\n"}

[bbernhard]

latest version should be capable of voice registration.

[Export33]

Thanks this worked.

I still had the authorization error. Deleting the data folder helped.