feat: show progress while waiting for framework server to start

[erezrokah]

Is your feature request related to a problem? Please describe.

Related to #3242 (comment)

When we start a framework server (e.g. Gatsby) we try to connect to the default port of that framework.
However, if a user configures a custom port they should tell netlify dev about it.

The problem is that netlify dev times out after 10 minutes and does't show any kind of progress while waiting for the framework server to start, so the user thinks the CLI is stuck and has not way of knowing what the problem is.

Most users won't wait 10 minutes for the CLI to timeout.

Describe the solution you'd like

The CLI should show some kind of progress while waiting to the framework server to start, detailing the port its trying to connect to and how to configure it.

This is a bit tricky since CLI logs are interleaved with the framework process logs

Describe alternatives you've considered

Possibly detecting the configured port, but that's a bigger lift

Additional context

#3242 (comment)

Can you submit a pull request?

Yes