* Leverage the getRuleSet method from ExplorationSteps to the more
  generic ProcessStep. It collects the RuleSets defined in a current and
  all parent ExplorationSteps.
* Use a newly added generic copy method that allows to copy multiple
  model elements while updating and fixing inter-model references of the
  contained elements.
* Create an ExplorationStep when the "Generate" button of a synthesis is
  pressed or a new RuleSet is added.
* Minor bug fixes & cleanup.

Issue-Ref: 3482
Issue-Url: https://af3-developer.fortiss.org/issues/3482


Signed-off-by: Alexander Diewald <diewald@fortiss.org>