Support for multiple credentialsSecretRefs

Hello,

Thank you for creating this!

I have a situation where I need to support multiple INWX accounts for multiple domains (where each domain is hosted in a separate INWX account). cert-manager supports using the dnsZones selector.

This means that I will have multiple secrets, one for each account, which needs to be read by your hook. Unfortunately, as far as I can tell it is not supported to pass multiple secrets to credentialsSecretRefs. It would be great if this could be added.

Thank you,

Alex