feat(admin, admin-ui, medusa-js, medusa-react, medusa): Support Admin Extensions (#4761)

Co-authored-by: Rares Stefan <948623+StephixOne@users.noreply.github.com>
Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

packages/admin-ui/ui/index.html

@@ -8,6 +8,5 @@
   </head>
   <body>
     <div id="root"></div>
-    <script type="module" src="/src/main.tsx"></script>
   </body>
 </html>