chore: Use namespace-scoped pull secrets for CP4BA

Contributes to: #112

Description of changes:

Pre-sync hook to create CP4BA pull secrets in target namespace
Reference pull secrets in CRs places according to docs
Removing old CP4BA-specific storage classes for ROKS (no longer needed in CP4BA 21.0.3)

Output of argocd app list command or screenshot of the ArgoCD Application synchronization window showing successful application of changes in this branch.

argocd app list
NAME                 CLUSTER                         NAMESPACE         PROJECT  STATUS  HEALTH   SYNCPOLICY  CONDITIONS  REPO                                    PATH                                  TARGET
argo-app             https://kubernetes.default.svc  openshift-gitops  default  Synced  Healthy  Auto-Prune  <none>      https://github.com/IBM/cloudpak-gitops  config/argocd                         112-gps-cp4ba
cp-shared-app        https://kubernetes.default.svc  ibm-cloudpaks     default  Synced  Healthy  Auto-Prune  <none>      https://github.com/IBM/cloudpak-gitops  config/argocd-cloudpaks/cp-shared     112-gps-cp4ba
cp-shared-operators  https://kubernetes.default.svc  ibm-cloudpaks     default  Synced  Healthy  Auto-Prune  <none>      https://github.com/IBM/cloudpak-gitops  config/cloudpaks/cp-shared/operators  112-gps-cp4ba
cp4a-app             https://kubernetes.default.svc  cp4a              default  Synced  Healthy  Auto-Prune  <none>      https://github.com/IBM/cloudpak-gitops  config/argocd-cloudpaks/cp4a          112-gps-cp4ba
cp4a-operators       https://kubernetes.default.svc  cp4a              default  Synced  Healthy  Auto-Prune  <none>      https://github.com/IBM/cloudpak-gitops  config/cloudpaks/cp4a/operators       112-gps-cp4ba
cp4a-resources       https://kubernetes.default.svc  cp4a              default  Synced  Healthy  Auto-Prune  <none>      https://github.com/IBM/cloudpak-gitops  config/cloudpaks/cp4a/resources       112-gps-cp4ba

IBM / cloudpak-gitops

chore: Use namespace-scoped pull secrets for CP4BA #114