Allow leader and follower headless service customization (annotations)

[madfromplay]

Is your feature request related to a problem? Please describe.
Hello! We are using redis-cluster operator to spin up dedicated redis-clusters per business application. In process of development we run a bunch of test jobs, which have to connect to redis from outside of kubernetes (we use EKS). At this moment there are no suitable way to discover redis-cluster from outside kubernetes

Describe the solution you'd like
As a solution - it would be great if we were able to annotate headless service with custom annotations, which could invoke external-dns to create FQDN for headless service in route53.

Describe alternatives you've considered
We can annotate services manualy after cluster setup, but this is way inconviniet

What version of redis-operator are you using?
redis-operator version: 0.11.0

Additional context
Unfortunately i can not find any way to affect service manifests which are created by operator through CRD. Enabling this feature would be awesome.

[iamabhishek-dubey]

Closed in #376