find free port based on node-portfinder package

[emiljas]

This is my proposal of finding a free port based on node-portfinder package.

The current solution cause a timeout in unit tests (> 2s on Windows machine).

[mention-bot]

By analyzing the blame information on this pull request, we identified @bpasero and @egamma to be potential reviewers

[msftclas]

Hi @emiljas, I'm your friendly neighborhood Microsoft Pull Request Bot (You can call me MSBOT). Thanks for your contribution!

This seems like a small (but important) contribution, so no Contribution License Agreement is required at this point. Real humans will now evaluate your PR.

TTYL, MSBOT;