New hook_ENTITY_TYPE_view_mode_alter() hook added.

New hook hook_ENTITY_TYPE_view_mode_alter() has been added to allow modules implement view mode alter hook for only specific entity types.

For Usage, the module developers have to replace ENTITY_TYPE with node, user etc. Examples below:
Before

function example_entity_view_mode_alter(&$view_mode, \Drupal\Core\Entity\EntityInterface $entity) {
    if ($entity->getEntityTypeId() == 'node' && $view_mode == 'full') {
      $view_mode = 'custom';
  }
}

After

function example_node_view_mode_alter(&$view_mode, \Drupal\Core\Entity\EntityInterface $entity) {
    if ($view_mode == 'full') {
      $view_mode = 'custom';
  }
}