Allow to add annotations to the managed ingress

[gioppoluca]

To use different ingresses, in the case also of multiple ingress controllers, it is needed to add some annotations. For example for traefik we need to add:

• kubernetes.io/ingress.class: my-ingress-class
• traefik.ingress.kubernetes.io/router.entrypoints: web, websecure

It could be useful to be able to specify it in the CR otherwise the option is to have the CR NOT manage the ingress, but is a pity.