Support 'nodetypes' configuration in Docbase field in Channel Manager

There is support for 'nodetypes' configuration on the Docbase field, similar to the Link type field, see Link Picker Configuration

This works in the content perspective but not in the Experience Manager (Visual editor). Docbase support was added there per CMS-15480 / CMS-15488.

Configuration example:

/hippo:namespaces/myproject/bannerdocument/editor:templates/_default_/docbase/cluster.options:    
  jcr:primaryType: frontend:pluginconfig
  *nodetypes: ['myproject:bannerdocument']

To do
a) the backend GET to fetch the document type configuration e.g. CMS/ws/content/documenttypes/myproject:bannerdocument lacks the 'nodetypes', see

b) the front-end should pass that config on to the picker