Print out names of remaining steps and tasks

[alenkacz]

What this PR does / why we need it:
This improves the debugging experience. Instead of getting something like "some tasks are not finished" we now get:

PlanExecution: 'everything' step(s) (instance: kudo-test-casual-horse/first-operator) of the deploy.main are not ready
PlanExecution: 'task' task(s) (instance: default/test-instance) of the test.phase.step are not ready