Sort imports from all files

Add "prettier" script in `package.json` to check if all files are
compliant.

Sort all imports and format all files by running `npm run lint -- --fix`
followed by `npm run prettier -- --write`.

Gitlab #29

Change-Id: Id80402d1344c3bc611f66a46cffeee5f2c375bd8
diff --git a/client/src/pages/addContactPage.jsx b/client/src/pages/addContactPage.jsx
index 0fbd21b..c1b242f 100644
--- a/client/src/pages/addContactPage.jsx
+++ b/client/src/pages/addContactPage.jsx
@@ -1,10 +1,10 @@
+import GroupAddRounded from '@mui/icons-material/GroupAddRounded';
+import { Box, Card, CardContent, Container, Fab, Typography } from '@mui/material';
 import { useNavigate } from 'react-router-dom';
 
-import { Box, Container, Fab, Card, CardContent, Typography } from '@mui/material';
-import GroupAddRounded from '@mui/icons-material/GroupAddRounded';
-import authManager from '../AuthManager';
-import { useAppDispatch } from '../../redux/hooks';
 import { setRefreshFromSlice } from '../../redux/appSlice';
+import { useAppDispatch } from '../../redux/hooks';
+import authManager from '../AuthManager';
 
 export default function AddContactPage(props) {
   const navigate = useNavigate();