EndpointGroupsManageRequest

Atomic batch of static endpoint group management operations. Operations are applied in order inside one transaction; either all commit or none do. `requestId` values must be unique within the request. Physical control is never part of this request. Every operation that writes a group advances its etag by one, so a later operation on a group already written in the same request must send the etag the earlier operation reports; each result reports the group's etag right after its operation.