chore: Add timeline to remove deprecated resourceCustomizations

[svghadi]

What type of PR is this?
/kind chore

What does this PR do / why we need it:
This PR adds removal timeline for deprecated resourceCustomizations. The resourceCustomizations was deprecated in v0.5.0 and is planned to be removed in v0.8.0.

Have you updated the necessary documentation?

• Documentation update is required by this PR.
• Documentation has been updated.

How to test changes / Special notes to the reviewer:

1. Run the operator locally using make install run
2. Create a argocd instance using deprecated resourceCustomizations field

   eg: https://argocd-operator.readthedocs.io/en/latest/reference/argocd/#resource-customizations-example

3. Execute kubectl get events | grep ResourceCustomizations
4. Observe that deprecation event was emitted

   9m19s       Warning   DeprecationNotice         argocd/example-argocd                               ResourceCustomizations is deprecated, and support will be removed in Argo CD Operator v0.8.0/OpenShift GitOps v1.10.0. Please use the new formats `ResourceHealthChecks`, `ResourceIgnoreDifferences`, and `ResourceActions`.
   

[jaideepr97]

/lgtm
thanks @svghadi