Adding --port setter to socket_server

[rhdeck]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

Right now, except for swift lanes, one cannot (without additional ruby code) run multiple fastlane socket server sessions. This would be really nice for parallelization, as well as for environments where localhost:2000 is otherwise spoken for.

Description

The start_server action gains an additional, optional parameter: -p port. This option (documented in the action itself) sets the port on localhost on which to mount the socket server. Takes four lines of code.

Testing Steps

fastlane action start_server -p 2001 &
nc localhost 2001

Happy connecting!

NB This change just adds three lines of code - it's a small change to open up a lot of power.

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[rhdeck]

@googlebot I signed it!

[googlebot]

CLAs look good, thanks!

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[rhdeck]

fwiw circleci says the fastlane.swift test (marked as pending on GH) is green

[fastlane-bot]

Hey @rhdeck 👋

Thank you for your contribution to fastlane and congrats on getting this pull request merged 🎉
The code change now lives in the master branch, however it wasn't released to RubyGems yet.
We usually ship about once a week, and your PR will be included in the next one.

Please let us know if this change requires an immediate release by adding a comment here 👍
We'll notify you once we shipped a new release with your changes 🚀

[fastlane-bot]

Congratulations! 🎉 This was released as part of fastlane 2.147.0 🚀