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/welcome.js b/client/src/components/welcome.js
index 7960820..a8738e9 100644
--- a/client/src/components/welcome.js
+++ b/client/src/components/welcome.js
@@ -1,6 +1,7 @@
 import { Button, Container } from '@mui/material';
 import { AnimatePresence, motion } from 'framer-motion';
 import { useState } from 'react';
+
 import JamiLogo from '../../public/jami-logo-icon.svg';
 
 const list = {