Add Views EntityReference filter to be available for all entity reference base fields

Fixes are made on on 11.x (our main development branch) first, and are then back ported as needed according to our policies.

In (widely used) contrib Drupal Commerce I think the product_id, referencing the parent product from paroduct variations is a good example that should work with, once this issue is finished?

// The product backreference, populated by Product::postSave().
    $fields['product_id'] = BaseFieldDefinition::create('entity_reference')
      ->setLabel(t('Product'))
      ->setDescription(t('The parent product.'))
      ->setSetting('target_type', 'commerce_product')
      ->setReadOnly(TRUE)
      ->setDisplayConfigurable('view', TRUE);

Will this need changes in the Drupal Commerce implementation or will this work out of the box, once this is finished? (Otherwise I'll open a Drupal Commerce issue to keep track of this).

The practical use case is to be able to filter by parent product in a list of Commerce Product Variations.

Actually looking back at ✨ Continuation Add Views EntityReference filter to be available for all entity reference fields Active I think this is outdated sorry! Because actually ✨ Configurable views filters to allow for different widgets Active will allow you to decide for whatever field whether you use entity reference or some other filter handler.