Add a list builder with support for bulk operations

The patch in #4 works great, many thanks!

I have made a few changes:

1. Fix code style violations.
2. Removed the 'primary' button type from the submit in line with Views bulk operations.
3. Replaced $action->execute() with $action->getPlugin()->executeMultiple() in line with the suggestion in #3017214-14: \Drupal\system\Entity\Action::execute() is missing from ActionConfigEntityInterface.

Removed the odd @throws lines from the test, and fixed a few more phpcs violations.

Thank you!

I've just tried using the BulkFormEntityListBuilder as a base class for my list builder but got heaps of errors as:

User error: "id" is an invalid render array key in Drupal\Core\Render\Element::children() (line 97 of core/lib/Drupal/Core/Render/Element.php).

What seems to be the issue is BulkFormEntityListBuilder:128 where instead of

$form[$this->entitiesKey][$entity->id()] = $this->buildRow($entity);

should in my opinion be:

$form[$this->entitiesKey]['#rows'][$entity->id()] = $this->buildRow($entity);

That said... if I do that I lose the checkboxes in the first column.

$form[$this->entitiesKey]['#options'][$entity->id()] = $this->buildRow($entity);

this will resolve checkbox disappear problem

The solution is slightly different:

• Use #type tableselect, not table. No need to attach the library manually.
• Then use #options as you suggested at the end.
• A #weight of 2 for the table and 1 for the header is advisable to get the same order as usual.

Caveat: it ruins the pager functionality by adding an extra one. The reason for this is render() calling load() and that, in turn, calling getEntityIds(). The pager gets added twice. I would call the form unconditionally instead:

public function render() {
  // Filter the actions to only include those for this entity type.
  $entity_type_id = $this->entityTypeId;
  $this->actions = array_filter($this->actionStorage->loadMultiple(), function (ActionConfigEntityInterface $action) use ($entity_type_id) {
    return $action->getType() == $entity_type_id;
  });

  return $this->formBuilder->getForm($this);
}