feature request: be able to test connectivity to a port w/ UDP or TCP

Sort of like the URL test, but more flexible...should optionally also check that data comes off the port when you put junk into it or it outputs something when connected to

Start by locating the existing URL test implementation and its configuration and test entry points. Define how TCP and UDP connectivity checks should be configured, including the optional behavior of sending junk data and verifying a response; done means both protocols and the response check are covered by tests and documented behavior.

Written by the indexing model from the issue text.