Move Socket.io to gatsby develop port

[aaronadamsCA]

It would be preferable for Socket.io to run on the same port as gatsby develop, not on a separate port.

Today, any environment that depends on port forwarding breaks the separate status port, for example:

• GitHub Codespaces and other containerized development environments.
  • Current workaround: set the unsupported INTERNAL_STATUS_PORT environment variable, then manually configure port forwarding.
• Ngrok, which only lets you tunnel one local port to an HTTPS Internet hostname. Internet hostnames are required for some dev scenarios, like OAuth.
  • No available workaround.

#28443 seemed to suggest the effort here isn't too high, so I hope it's something you'll consider.

[ZeldOcarina]

Hi! Can you please expand on INTERNAL_STATUS_PORT?