refactor RBAC permissions for cluster-csi-snapshot-controller-operator

The ClusterRole and ClusterRoleBinding for csi-snapshot-controller are currently created in https://github.com/openshift/cluster-csi-snapshot-controller-operator/blob/master/manifests/05_operand_rbac.yaml 

This manifest is applied by CVO, not by cluster-csi-snapshot-controller-operator. Fabio pointed out one problem with this is that the ClusterRoleBinding in this manifest references a ServiceAccount that is created by the operator later:
https://github.com/openshift/cluster-csi-snapshot-controller-operator/blob/master/assets/serviceaccount.yaml

So the RBAC permissions in manifests/05_operand_rbac.yaml should be created by cluster-csi-snapshot-controller-operator instead of CVO. This means though that the operator needs the same permissions in manifests/05_operator_clusterrole.yaml so that it can grant them to the operand.

1. Move manifests/05_operand_rbac.yaml to assets/rbac/ and add this manifest to pkg/operator/starter.go
2. Add required permissions to manifests/05_operator_clusterrole.yaml so the operator can create the ClusterRoles for csi-snapshot-controller and csi-snapshot-webhook
3. Remove manifests/06_operator_operand_clusterrolebinding.yaml

4.16.0    

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csi-snapshot-controller ClusterRole is created by CVO

csi-snapshot-controller ClusterRole should be created by cluster-csi-snapshot-controller-operator