Emit build operation progress events for logging output (#4537) * Tweak BuildOperationListener#progress api * Use build operation id to reference progress * Add workaround for tracing log output via build operation progress for composite builds * Replace some Object typing of operation identifiers with OperationIdentifier. * Associate all progress logging with the current build operation. * Update logic to accommodate for all progress events now having build operation IDs. * Don't allow ProgressStartEvent.buildOperationCategory to be null. ** Default it to uncategorized.