Fix RaDataTable-rowCell CSS class is not applied on <DataTable> cells

Author: djhi

packages/ra-ui-materialui/src/list/datatable/DataTable.stories.tsx

@@ -239,6 +239,9 @@ export const SX = () => (
                 '& .RaDataTable-rowOdd': {
                     backgroundColor: '#fee',
                 },
+                '& .RaDataTable-rowCell': {
+                    color: 'red',
+                },
             }}
         >
             <DataTable.Col source="id" />

packages/ra-ui-materialui/src/list/datatable/DataTableCell.tsx

@@ -6,6 +6,7 @@ import get from 'lodash/get';
 import clsx from 'clsx';
 
 import { DataTableColumnProps } from './DataTableColumn';
+import { DataTableClasses } from './DataTableRoot';
 
 const PREFIX = 'RaDataTableCell';
 
@@ -55,6 +56,7 @@ export const DataTableCell = React.memo(
                 <TableCellStyled
                     ref={ref}
                     className={clsx(
+                        DataTableClasses.rowCell,
                         className,
                         cellClassName,
                         `column-${source}`