test: add coverage for app.listen() variants

[kgarg1]

• verify alternate signatures (port+host+backlog)
• verify server.address() shape

[bjohansebas]

thanks @kgarg1!

[wesleytodd]

Not going to ask that these be backed out, but they are testing Node.js apis not Express ones. I know it looks like they are testing listen, but the actual assertions are not.

Typically we don't want to test anything other than our api. I would prefer if we could take a second look at these and try to compare the coverage the add for express code and modify them to better test what that express is correctly passing the values to Node.js.