Issue #3266343: Complete logic for searching all languages

In several places, the existence of multiple translations of
a given Node or Paragraph is now taken into account when searching.
Also, render array now includes URLs for viewing and editing
Nodes associated with these matches; default logic in
Twig template was not taking multiple languages into account.

WIP. Replace and undo methods still not fully evaluated for
correctness in light of multiple languages.

This edit is minimally invasive. A few early returns were
added for refactoring, but that was only to make the logic
easier to follow and to be less nested. These methods still
contain considerable duplicated code which could likely
be refactored into the Entity base class, but that is a
separate issue.