Some config entities do not respect uri callbacks

Block, Shortcut and View config entities do not respect URI callbacks specified via entity info (see the EntityManager class). They directly override Entity::uri() as follow what skips the logic to take account of the entity uri callback:

  /**
   * Overrides Drupal\Core\Entity\EntityInterface::uri().
   */
  public function uri() {
    return array(
      'path' => 'admin/structure/views/view/' . $this->id(),
    );
  }

We should a) fix this and b) improve docs that is clear how this is supposed to work.

Related issues:
#1899816: Various config entity types are missing URI callbacks
#1803586: Give all entities their own URI