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/messenger.jsx b/client/src/pages/messenger.jsx
index f8d5907..3108fe6 100644
--- a/client/src/pages/messenger.jsx
+++ b/client/src/pages/messenger.jsx
@@ -1,18 +1,18 @@
+import { Stack } from '@mui/material';
 import { useEffect, useState } from 'react';
-import Header from '../components/Header';
-import NewContactForm from '../components/NewContactForm';
+import { useParams } from 'react-router';
 
+import Contact from '../../../model/Contact';
+import Conversation from '../../../model/Conversation';
+import { useAppSelector } from '../../redux/hooks';
+import authManager from '../AuthManager';
 //import Sound from 'react-sound';
 import ConversationList from '../components/ConversationList';
-import authManager from '../AuthManager';
-import Conversation from '../../../model/Conversation';
-import Contact from '../../../model/Contact';
 import ConversationView from '../components/ConversationView';
-import AddContactPage from './addContactPage.jsx';
+import Header from '../components/Header';
 import LoadingPage from '../components/loading';
-import { useParams } from 'react-router';
-import { Stack } from '@mui/material';
-import { useAppSelector } from '../../redux/hooks';
+import NewContactForm from '../components/NewContactForm';
+import AddContactPage from './addContactPage.jsx';
 
 const Messenger = (props) => {
   const { refresh } = useAppSelector((state) => state.app);