Note

I split the "Filter out unwanted content from a Norsu node" part into this ticket: 

https://jira.magnolia-cms.com/browse/PAGES-1113

Original Description

For the purpose of navigation components, we need a way to retrieve subpages through the delivery endpoint.

In JCR, we can define an endpoint that only returns child nodes with a specific type. E.g. to get only subpages to build a navigation component, we define:

class: info.magnolia.rest.delivery.jcr.v2.JcrDeliveryEndpointDefinition
workspace: website
depth: 1
childNodeTypes: # defaults to mgnl:contentNode, returning only areas and components
  - mgnl:page 

Norsu rest endpoint should probably have analogous functionality, so we can avoid client-side workarounds like this.