Operator 3.0.0 Release Candidate 1

Adds Model in Image feature. Support for Kubernetes 1.16. Removal of support for Kubernetes 1.13 and earlier. Removal of support for Helm 2.x. This release candidate cannot be run in the same cluster as another release of the operator. You can upgrade from 2.5.0 to 3.0.0-rc1 without needing to restart or recreate any existing domains. However, please note that we do plan to support running the final 3.0.0 release in the same cluster with at least one 2.x release of the operator to allow for staged migration.