Issue #2183923 by tim.plunkett: Break the circular dependency in EntityManager.

core/core.services.yml

core/includes/entity.inc

core/lib/Drupal/Core/Controller/ControllerBase.php

core/lib/Drupal/Core/Entity/EntityFormBuilder.php

core/lib/Drupal/Core/Entity/EntityFormBuilderInterface.php

core/lib/Drupal/Core/Entity/EntityManager.php

core/lib/Drupal/Core/Entity/EntityManagerInterface.php

...lib/Drupal/aggregator/Controller/AggregatorController.php

.../Drupal/custom_block/Controller/CustomBlockController.php

.../block/lib/Drupal/block/Controller/BlockAddController.php

core/modules/comment/comment.module

...mment/lib/Drupal/comment/Controller/CommentController.php

...nfig_test/lib/Drupal/config_test/ConfigTestController.php

...ntact/lib/Drupal/contact/Controller/ContactController.php

...modules/content_translation/content_translation.pages.inc

...les/forum/lib/Drupal/forum/Controller/ForumController.php

...odules/menu/lib/Drupal/menu/Controller/MenuController.php

...odules/node/lib/Drupal/node/Controller/NodeController.php

...les/options/lib/Drupal/options/Tests/OptionsFieldTest.php

.../search/lib/Drupal/search/Controller/SearchController.php