Issue #2024833 by claudiu.cristea: Adopt load() and loadMultiple() on entity storage controllers.

core/includes/bootstrap.inc

core/includes/entity.inc

core/includes/menu.inc

...lib/Drupal/Core/Config/Entity/ConfigStorageController.php

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

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

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

...b/Drupal/Core/Entity/EntityStorageControllerInterface.php

core/lib/Drupal/Core/ParamConverter/EntityConverter.php

...les/action/lib/Drupal/action/ActionFormControllerBase.php

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

...les/aggregator/lib/Drupal/aggregator/Form/OpmlFeedAdd.php

...gator/lib/Drupal/aggregator/Plugin/views/argument/Fid.php

...gator/lib/Drupal/aggregator/Plugin/views/argument/Iid.php

core/modules/block/custom_block/custom_block.module

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

...modules/block/lib/Drupal/block/BlockStorageController.php

...les/block/lib/Drupal/block/Tests/BlockStorageUnitTest.php

...s/block/lib/Drupal/block/Tests/Views/DisplayBlockTest.php

core/modules/book/lib/Drupal/book/BookManager.php