Issue #2011018 by tim.plunkett: Reconcile entity forms and confirm forms.

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

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

core/lib/Drupal/Core/Form/ConfirmFormBase.php

core/lib/Drupal/Core/Form/ConfirmFormInterface.php

core/modules/action/action.module

core/modules/action/action.routing.yml

...odules/action/lib/Drupal/action/Form/ActionDeleteForm.php

core/modules/aggregator/aggregator.module

core/modules/aggregator/aggregator.routing.yml

...odules/aggregator/lib/Drupal/aggregator/FeedInterface.php

.../aggregator/lib/Drupal/aggregator/Form/FeedDeleteForm.php

...aggregator/lib/Drupal/aggregator/Form/FeedItemsDelete.php

...egator/lib/Drupal/aggregator/Form/FeedItemsRemoveForm.php

...regator/lib/Drupal/aggregator/Plugin/Core/Entity/Feed.php

core/modules/ban/lib/Drupal/ban/Form/BanDelete.php

core/modules/block/block.routing.yml

core/modules/block/lib/Drupal/block/Form/BlockDeleteForm.php

...dules/block/lib/Drupal/block/Plugin/Core/Entity/Block.php

.../modules/config/tests/config_test/config_test.routing.yml

...test/lib/Drupal/config_test/Form/ConfigTestDeleteForm.php