Automatically add CNAME record on DNS DCV method

[piloos]

In the past (Gandi V4 CLI), we could use the auto DCV method. This would use the dns method and would automatically add the correct CNAME record (of course if the domain was registered with Gandi).

This is no longer possible in the current (v1.4) Gandi CLI. It does not support the auto DCV method anymore. The only workaround is to chose the dns method and add the CNAME record manually.