[JENKINS-23080]

Get rid of the FlowExecutionOwner.getConsole() method, and implement print in terms of echo step.

This doesn't handle print() without NL correctly. For that, FlowNode needs to be explicitly added with log, and adjacent print family calls need to be smart enough to combine their outputs into a single FlowNode.

I don't have cycles to do that right now, but this change at least removes unwanted call from API.
Merge commit 'bf734ffebe47a67b88638bd398ff7f39e2856eeb'