feat: Support objectOverrides

[sbernauer]

Description

Needs stackabletech/operator-rs#1118

Current WIP! state:

apiVersion: zookeeper.stackable.tech/v1alpha1
kind: ZookeeperCluster
metadata:
  name: simple-zk
spec:
  image:
    productVersion: 3.9.4
  servers:
    roleGroups:
      default:
        replicas: 1
  # NEW
  objectOverrides:
    - apiVersion: apps/v1
      kind: StatefulSet
      metadata:
        name: simple-zk-server-default
        namespace: default
        labels:
          custom: label
      spec:
        replicas: 2
        podManagementPolicy: Parallel
    - apiVersion: v1
      kind: ServiceAccount
      metadata:
        name: simple-zk-serviceaccount
        namespace: default
        labels:
          im-on: AWS
        annotations:
          custom: AWS
    - apiVersion: policy/v1
      kind: PodDisruptionBudget
      metadata:
        name: simple-zk-server
        namespace: default
      spec:
        maxUnavailable: 42
  # OLD
  # objectOverrides: |
  #   apiVersion: apps/v1
  #   kind: StatefulSet
  #   metadata:
  #     name: simple-zk-server-default
  #     namespace: default
  #     labels:
  #       custom: label
  #   spec:
  #     replicas: 2
  #     podManagementPolicy: Parallel
  #   ---
  #   apiVersion: v1
  #   kind: ServiceAccount
  #   metadata:
  #     name: simple-zk-serviceaccount
  #     namespace: default
  #     labels:
  #       im-on: AWS
  #     annotations:
  #       custom: AWS
  #   ---
  #   apiVersion: policy/v1
  #   kind: PodDisruptionBudget
  #   metadata:
  #     name: simple-zk-server
  #     namespace: default
  #   spec:
  #     maxUnavailable: 42

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

Author

• Changes are OpenShift compatible
• CRD changes approved
• CRD documentation for all fields, following the style guide.
• Helm chart can be installed and deployed operator works
• Integration tests passed (for non trivial changes)
• Changes need to be "offline" compatible
• Links to generated (nightly) docs added
• Release note snippet added

Reviewer

• Code contains useful comments
• Code contains useful logging statements
• (Integration-)Test cases added
• Documentation added or updated. Follows the style guide.
• Changelog updated
• Cargo.toml only contains references to git tags (not specific commits or branches)

Acceptance

• Feature Tracker has been updated
• Proper release label has been added
• Links to generated (nightly) docs added
• Release note snippet added
• Add type/deprecation label & add to the deprecation schedule
• Add type/experimental label & add to the experimental features tracker