Update the docs about medialibrary to be compatible with groups v2 and v3

Problem/Motivation

use Drupal\views\Plugin\views\query\QueryPluginBase;
use Drupal\views\ViewExecutable;
use Drupal\group\Entity\Group;
use Drupal\group\Entity\GroupRelationship;
use Drupal\node\Entity\Node;
use Drupal\Component\Plugin\Exception\PluginNotFoundException;


/**
 * Implements hook_views_query_alter().
 */
function group_media_library_views_query_alter(ViewExecutable $view, QueryPluginBase $query) {
  if ($view->id() == 'media_library') {
    // When media_library is being used to add
    // media to a node, we try to limit
    // the available media to only those that belong
    // to the group the node belongs to.
    // We have no way of knowing if media_library
    // is being used in this context, so we try
    // to get the group id from the current URL.
    $groups = [];
    $group = \Drupal::request()->attributes->get('group');
    if (empty($group) || !$group instanceof Group) {
      $node = \Drupal::request()->attributes->get('node');
      if (empty($node) && $view->getExposedInput()['media_library_opener_parameters']['entity_type_id'] == 'node') {
        $exposed_nid = $view->getExposedInput()['media_library_opener_parameters']['entity_id'];
        $node = Node::load($exposed_nid);
      }
      if (!empty($node) && $node instanceof Node) {
        foreach (GroupRelationship::loadByEntity($node) as $group_relationships) {
          // If it's linked to more than one then it will grab the group
          // entity->id of the last linked group only so push to groups array
          $group_id = $group_relationships->gid->entity->id();
          $groups[] = Group::load($group_id);
        }
      }
    } else {
      // add group from request to array to be as iterable as it was
      // a node with multiple relationships to multiple groups.
      $groups[] = $group;
    }

    if(!empty($groups)) {
      $media_ids = [];
      \Drupal::messenger()->addMessage(t('Adding new media with this dialog will grant access to this media for group members.'));
      foreach ($groups as $group) {
        if (!empty($group) && $group instanceof Group) {
          // Get all media types (bundles).
          $bundle_info = \Drupal::service('entity_type.bundle.info')->getBundleInfo('media');
          $bundle_info_plugin_prefixed = array_map(fn($media_bundle): string => "group_media:$media_bundle", array_keys($bundle_info));
          $installed_plugins = \Drupal::service('group_relation_type.manager')->getInstalled($group->getGroupType());
          // which media types/bundles are enabled as group relationship
          $media_plugins = array_intersect($bundle_info_plugin_prefixed,$installed_plugins->getInstanceIds());
          // Get group relationship for each media bundle.
          foreach ($media_plugins as $media_plugin) {
            try {
              $group_relationships = $group->getRelationships($media_plugin);
            } catch (PluginNotFoundException $exception) {
              continue;
            }

            if (!empty($group_relationships)) {
              // Get id of each media.
              foreach ($group_relationships as $group_relationship) {
                $media_ids[] = $group_relationship->get('entity_id')->getValue()[0]['target_id'];
              }
            }
          }
        }
      }
      // Restrict media to only those in group.
      // if needs to list only media of this group or public media.
      // Comment next if block if you want to list public media too.
      if(empty($media_ids)) {
        $media_ids[] = -1;
      }
      if (!empty($media_ids)) {
        $media_relationship_data = $query->setWhereGroup('AND');
        $query->addWhere($media_relationship_data, 'media_field_data.mid', $media_ids, 'IN');
      }
    }
  }
}