Split VocabularyFormController into VocabularyAddForm and VocabularEditForm

Updated: Comment #0

Problem/Motivation

#2214063: 'Add vocabulary' page doesn't display correct page title. → introduced a if ($entity->isNew()) {} check to VocabularyFormController. We're trying to avoid such checks in favor of dedicated form classes for add and delete forms which inherit from a base form class.

Proposed resolution

• Rename VocabularyFormController to VocabularyFormBase and move it into the Drupal\taxonomy\Form namespace
• Create a Drupal\taxonomy\Form\VocabularyAddForm and a Drupal\taxonomy\Form\VocabularyEditForm that both extend VocabularyFormBaseand move the declaration of $form['#title'] there.
• Register the new forms in the entity annotation
• Profit

Remaining tasks

User interface changes

API changes