[RFE] add support of the --signature-version option to support either v2 or v4 versions Reported by: matthiasmuench https://access.redhat.com/documentation/en-us/red_hat_openshift_container_storage/4.5/html/managing_openshift_container_storage/multicloud-object-gateway_rhocs#annotations:9677ae7e-386e-4b98-aee9-b83db9f61edd