Change named exports to default exports for mui icons

This is to reduce transfer size when users load the page for the first time

Change-Id: I3215b7099bcdbea7b446da599810f5951407bbdb
diff --git a/client/src/components/FilePreview.tsx b/client/src/components/FilePreview.tsx
index 68c3424..0b3e506 100644
--- a/client/src/components/FilePreview.tsx
+++ b/client/src/components/FilePreview.tsx
@@ -15,7 +15,7 @@
  * License along with this program.  If not, see
  * <https://www.gnu.org/licenses/>.
  */
-import { AttachFile } from '@mui/icons-material';
+import AttachFile from '@mui/icons-material/AttachFile';
 import { IconButton, IconButtonProps, Stack, Typography } from '@mui/material';
 import * as mime from 'mime';
 import { useRef } from 'react';