Random port configuration of port in tests

[lordofthejars]

Currently, there is one property called quarkus.http.test-port where you can set the port number where to start the Quarkus server, but we should provide a special char for setting a random private port (49152 through 65535)

I purpose something like quarkus.http.test-port=$

This is important for allowing the system to execute tests in parallel.

If agrees I can send a PR.

[starksm64]

Just use 0 as that is the normal linux way of binding to a system defined random port and could just work on many systems.

[lordofthejars]

Ok, then please assign me this issue and when I finish my current Quarkus issue, I'll start working on it.

[gastaldi]

I gave a shot at this and implemented #4140. I'd appreciate a review ;)