Adds annotations to CiliumNetworkPolicies

What does this MR do?

Adds annotations to CiliumNetworkPolicies. This MR adds annotations as part of metadata for CiliumNetworkPolicies wrapper. With this change policy editor can send annotations as part of the payload when creating/updating network policies.

It unblocks the following issue: #238484 (closed)

Example of the outcome of this change within the cluster:

$ kubectl get ciliumnetworkpolicy -n network-policy-demo-20-production test-annotations -o yaml
apiVersion: cilium.io/v2
kind: CiliumNetworkPolicy
metadata:
  annotations:
    app.gitlab.com/alert: "true"
  creationTimestamp: "2020-12-24T19:38:03Z"
  generation: 1
  name: test-annotations
  namespace: network-policy-demo-20-production
  resourceVersion: "30992"
  selfLink: /apis/cilium.io/v2/namespaces/network-policy-demo-20-production/ciliumnetworkpolicies/test-annotations
  uid: 24b2cb3f-244e-4249-a85d-ef8a59a7d302
spec:
  endpointSelector:
    matchLabels:
      network-policy.gitlab.com/disabled_by: gitlab

Screenshots (strongly suggested)

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Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team