Manage DNS records

[ayys]

This adds subcommands to manage domains and DNS records.
This PR gives you the ability to list, get, and sync zone files for domains.

Merges PR #4483

$ wasmer domains list # list all domains

$ wasmer domains list <namespace> # list all domains in the namespace

$ wasmer domain get <domain-name>

$ wasmer domain get-zone-file <domain-name>

$ wasmer domain sync-zone-file <zone-file> [--no-delete-missing-records]