Add ability to dynamically set limit on EntityListBuilder

\Drupal\Core\Entity\EntityListBuilder() has a hardcoded limit of 50 entities, at which it paginates. This is a fine default, but there's no way to override it dynamically, making it unusable for any use case that requires the entire list (such as the node/add, page, for example--see #2693485: Content types are ordered by machine name on /node/add page (+ similar issues with other entities)). It would sure be nice to have a public setLimit() method. Patch to follow.