XD-2496 - Refactor use of getContainerHostForSource in integration tests

* Created ContainerResolver for looking up runtime location of a module.
* Added httpSource and other xyzSource methods that take a stream name.
* Updated assertReceived to assertReceivedBySink/Source/Processor.
Updated code based on code review.
Show 'asciidoctorHtml' when executing `./gradlew tasks`