add a checkport.java to check open necessary ports

[maxandersen]

idea i got when having to manually run lsof.

this is a script portable on all OS and runs using plain java (jbang instructions just there for ./checkports.java exec)

[github-actions]

🚀 PR Preview debbb99 has been successfully built and deployed to https://quarkiverse-quarkus-workshops-pr-349-preview.surge.sh

[agoncal]

Really nice

[agoncal]

@maxandersen what about merging the PR and documenting the usage of this utility class ?

[holly-cummins]

I put a comment somewhere, but I've misplaced it, because don't see it here ... I like this script a lot, but I'm not sure the workshop is the right place for it. My preference in the workshop is that we stick to first principles, and teaching people to fish rather than giving them scripts that fish for them.

If we teach workshop participants how lsof can solve their problems in general, they're really getting something out of the workshop. @maxandersen pointed out that lsof doesn't work on windows, so we'd need a guard and a netstat command, but that's easy to do. To me, that's more educational than the checkports script ... but I think we should find somewhere for the checkports script where it can be used by a bigger audience, like in the quarkus cli.