defective elements

[a-gerhard]

It is not possible to stop or destroy elements on an unreachable host. This means that it is impossible to use the element, and to modify parts of the topology, or delete the topology. For elements on problematic hosts, there should be a force-destroy action that removes the association between the element its hostElement. the hostElement will be deleted by the backend as soon as possible, and the element is set to the created state so that it can prepared again or deleted.

• [x] allow orphaned hostelements and hostconnections
  • this means that the hostelement is not related to an element in a topology.
• [x] add a task that regularly tries to delete orphaned elements
• [ ] add a force-destroy action.
  • available when host has problems, and element is prepared or started
  • orphanes the hostelement and resets the element to created state
  • find out how to handle child or parent elements and connections related to the respective element.

[a-gerhard]

The second task is related to #1423