debugger: bind to random port with --inspect=0

[develar]

As #5025, but for --inspect. #5025 (comment)

[bmeck]

I am guessing you would also want/need the url to load up in devtools?

[after-ephemera]

I'd love to take a shot at helping on this. Can someone direct me where to start?

[cjihrig]

@azjkjensen this is probably a good place to start. Allowing 0 here seems to make it work for me, but I didn't run the full test suite, and there could be other nuances.

[after-ephemera]

@cjihrig are you suggesting that I just add a check for if result == 0 or do I need to add the random port logic as well?

[cjihrig]

@azjkjensen I was suggesting allowing result == 0.

[after-ephemera]

@cjihrig it looks like that change works, I just need to write a test for it and then I'll make a PR. Is a single test usually sufficient for a change like this? This is my first time contributing so such a large project.

[refack]

Is a single test usually sufficient for a change like this?

Use your judgment, if you can think of more than one relevant situation write more than one test...
Good place to look is at test that already check --inspect or --inspect-brk like test/parallel/test-debug-brk.js