Use ActionDialog and NodeDialog

Based on I70e88f6 in VE core

* Cleanup dialogs by using node dialog and action dialog
* Move "Loading..." text from label of dialog apply button to dialog title
  (repurpose identical message)

Save dialog will be converted in a follow up.

Change-Id: I6a290f4bdc29e577c7c89b4babdab5853c4c10e5