TEIIDDES-1712: Refactors and simplifies object delete command

* Remove the remaining complexity of the ObjectDeleteCommand by merging it
  with its parent class ResourceRefactorCommand. Since the latter is only
  used now by the former, its unnecessary. The parent class is geared
  towards resources rather than eObjects so it makes little sense for the
  ObjectDeleteCommand to extend it anyway.

* ResourceRefactorCommand deleted and references removed