Changes to add OCI feature to configmanagement gke hub feature

[modular-magician]

Updated DCL version to 1.28.0 to support OCI Config in google_gke_hub_feature_membership .
Added OCI config feature in google_gke_hub_feature_membership::configmanagement::config_sync .

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anthos-fleet-management: added feature `configmanagement:config_sync:oci` to resource `google_gke_hub_feature_membership`.

Derived from GoogleCloudPlatform/magic-modules#6901