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/components/SendMessageForm.js b/client/src/components/SendMessageForm.js
index d46883c..69e6b6e 100644
--- a/client/src/components/SendMessageForm.js
+++ b/client/src/components/SendMessageForm.js
@@ -1,5 +1,7 @@
-import { useState, useCallback } from 'react';
 import { Divider, InputBase } from '@mui/material';
+import { Stack } from '@mui/system';
+import { useCallback, useState } from 'react';
+
 import {
   RecordVideoMessageButton,
   RecordVoiceMessageButton,
@@ -7,7 +9,6 @@
   SendMessageButton,
   UploadFileButton,
 } from './buttons';
-import { Stack } from '@mui/system';
 
 export default function SendMessageForm(props) {
   const [currentMessage, setCurrentMessage] = useState('');