Remove depreciated methods and unused imports in code base.

Thanks for the patch.

Suggestions:

• Update property and variable names from ::entityManager to ::entityTypeManager and from $entity_manager to $entity_type_manager. See e.g. the property and variable names used in EntityBundleListener.
• Make sure to update the code documentation to reflect the new object type used in class properties and constructors. Examples:
  

    /**
     * The entity manager.
     *
     * @var \Drupal\Core\Entity\EntityManagerInterface
     */
    protected $entityManager;
  

     * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
     *   The entity manager.
  

That looks good, thanks! I think it may conflict with some similar work done as part of #2659178: Add delete capability, so I think I'll wait to commit this for a bit.

Sorry, I forgot about this... and indeed it doesn't apply any more.

Thanks! I can definitely apply this patch... but:

1. +++ b/src/ConfigLister.php
   @@ -62,7 +62,7 @@ class ConfigLister implements ConfigListInterface {
   -   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
   +   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_manager
   

   I thought in the last version of this patch, besides using EntityTypeManagerInterface, it also changed the local/member variable names to $entity_type_manager? That seemed like a good idea.

2. +++ b/src/ConfigReverter.php
   @@ -61,7 +61,7 @@ class ConfigReverter implements ConfigRevertInterface, ConfigDeleteInterface {
   +   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_manager
   

   Here too.

Although I guess that changing even protected member variable names is probably not a good idea... so OK, let's leave the variable names as-is. I'll just commit this. Thanks again!