Next step in allowing users to attach Toolpad to an existing node http server

• Isolate the Toolpad router
• Run the websocket server on its own port (necessary because the router doesn't necessarily have access to the server it is running on)
• Avoid running the websocket server in production
• moving bashResolvePath to @mui/toolpad-utils/cli. @mui/toolpad-utils/path is used in the browser, it shouldn't import os or path. (a vite warning I noticed while working on this)

To do in follow up PRs:

• basePath support. People want to run this as part of their own servers. Therefore we need to allow attaching the router under a basePath
• allow optional reuse of httpServer for the websocket (need basePath support first for correct namespacing)
• expose function publicly
• documentation