Changed collection hierarchy management to column view

[mmiche01]

Changed whole collection management to use a columnbased view instead of a table-based one. The start view is now a column with top-level collections (no outgoing PART_OF relationships). By clicking on the entries, users can navigate down the PART_OF relationships to collections below. The navigation path is stored in the URL, so on reload, the path opens again.

Key changes:

• Created new Components Column Viewer, columns, breadcrumbs, edit panes etc., removed old components
• Change API pagination from page-based to cursor-based (for infinite scrolling)