Add Zone import support

[sbastn]

Description

The API supports importing a zone file, but I couldn't find this command on the CLI. I would expect it to be along the lines dnsimple zone import filename.txt.

Expected Behavior or Outcome

• Having support for zone file imports

Acceptance Criteria

• Running dnsimple zone import filename.txt should import my zone file.

Resources/References

https://support.dnsimple.com/articles/import-records-zone-file/

Notes

None