Split up the rdf mapping report

[dannylamb]

Follow up to Islandora/islandora#835

The display of all the rdf mappings may eventually crash on a large enough system. @elizoller suggested leaving the content types on a single page, but providing links to each vocabulary so it can be on its own page. That should sufficiently break apart the content so too much is never rendered onto a single page.

[mjordan]

2021-05-05 Tech Call consensus that separating out each vocab into its own tab, and within each tab, provide pagination to reduce load on Drupal.

[mjordan]

http://www.jessenicola.com/blog/drupal-8-add-tab-custom-controller explains how to create hard-coded tabs in a custom controller, but I'm not sure if it's possible to render dynamically-generated tabs in one. Maybe just a list of vocabs, each leading to the mappings in the linked vocab, would suffice?