Promote EnterpriseSearch to v1

[pebrc]

What is the impact for existing users on all supported platforms e.g. OpenShift 3.11

Let's promote the EnterpriseSearch CRD to v1 given that we consider it to have reached GA status and we consider the API stable at this point.

[pebrc]

Doing some GH archaeology, we ran into issues with older versions of k8s mainly v1.11 and unpatched versions of 1.12 and 1.13

Underlying kubernetes/kubernetes#73752

#2308 has the relevant ECK discussion from back then. We decided to recommended reinstalling all custom resources back then for users on affected k8s versions. This was acceptable back then as ECK was still alpha. We cannot use the same approach this time round.

Options as I see them:

• do not upgrade the API schema version
• do upgrade the API schema version but document that users on older versions of k8s will have to disable the webhook or to change the API version of existing resources back to v1beta1 by manual edit
• wait with this change until we don't have to support the older k8s versions anymore

[pebrc]

The impact of migrating to v1 is somewhat limited by the fact that patched k8s versions exist for > 1.12 and that OpenShift 3.11 by default has the validating admission webhook disabled. So that documenting the workaround for the small number of users potentially affected seems like a viable option.