Leverage page provider pagination in nuxeo-document-tree

Currently, the nuxeo-document-tree element uses the tree_children page provider and displays only the first page of the child documents (40 by default).

In order to display more doc, the only solution is to increase the page size of the tree_children page provider which won't scale after few hundreds of child documents.

We need to introduce a way to use the pagination provided by the page provider either by:

• infinite scrolling
  or
• add a load more node to load next page.