TEIIDDES-1594: Refresh the server panel on name change of the server

* Adds an execution configuration listener to the server panel so that
  the text will be updated if the default server receives any configuartion
  updates, such as custom label.
Restrict the preview import vdb functionality to teiid 8+ servers

* Restores the merge method to Teiid 7 ExecutionAdmin, only allowing the
  import vdb functionality to 8+ servers.

* Merge should remain deprecated since it is only for backward compatibility