Enable policies for cert-manager.

[Yannig]

Fix for #745

Description

Checklist

• Code compiles correctly (i.e make build)
• Added tests that cover your change (if possible)
• All unit tests passing (i.e. make test)
• All integration tests passing (i.e. make integration-test)
• Added/modified documentation as required (such as the README.md, and examples directory)
• Added yourself to the humans.txt file

[errordeveloper]

@Yannig thanks very much! This looks good overall, but I wonder if we should make this controlled by a dedicated config field instead of hanging it on externalDNS – what do you think?

[Yannig]

@errordeveloper no problem. I'm doing it asap.

[Yannig]

@errordeveloper what do you think about it?

[errordeveloper]

@Yannig thank you, this looks good! Ideally, we would make this a config-only option, if you are okay with that? We have a strong preference to avoid adding new flags, as there are already too many.

[Yannig]

I understand. I'm doing the modification.

[Yannig]

@errordeveloper I think it's fine now. What do you think about?

[errordeveloper]

This looks good! If you have a moment to replace new PolicyExternalDNS strings with PolicyCertManager, it would be great, otherwise I'm happy to follow up.

[Yannig]

Done