Computed fields can now be displayed by Views

Views is a query builder at heart, so generally just displays fields that have database columns associated with them.

Now Views can also support computed fields to display fields that don't have associated database columns.

Example from \Drupal\entity_test\EntityTestViewsData mapping an entity's computed field to Views:

      $views_data['entity_test_computed_field']['computed_string_field'] = [
        'title' => $this->t('Computed String Field'),
        'field' => [
          'id' => 'field',
          'default_formatter' => 'string',
          'field_name' => 'computed_string_field',
        ],
      ];