Stop reads and writes on datanodes during major upgrades

Some backwards incompatible changes like HDDS-4866 may need to reformat containers or volumes during upgrade. We currently cannot safely do this during finalize because we do not block reads on the datanode while it is finalizing, only writes. This jira is to investigate having an option to block writes on datanodes during finalization of more invasive upgrade actions, while leaving the normal read only requirement for minor upgrade changes.