Internal: Add index to resource link with sortable groups - refs BT#22193

```sql
CREATE INDEX idx_resource_link_sortable_groups ON resource_link (c_id, session_id, usergroup_id, group_id, user_id, resource_type_group);
```

src/CoreBundle/Entity/ResourceLink.php

@@ -22,6 +22,10 @@ use Symfony\Component\Serializer\Annotation\Groups;
 
 #[ApiResource]
 #[ORM\Table(name: 'resource_link')]
+#[ORM\Index(
+    columns: ['c_id', 'session_id', 'usergroup_id', 'group_id', 'user_id', 'resource_type_group'],
+    name: 'idx_resource_link_sortable_groups'
+)]
 #[ORM\Entity(repositoryClass: ResourceLinkRepository::class)]
 #[Gedmo\SoftDeleteable(fieldName: 'deletedAt', timeAware: false, hardDelete: true)]
 class ResourceLink implements Stringable

src/CoreBundle/Migrations/Schema/V200/Version20170525122900.php

@@ -38,7 +38,7 @@ class Version20170525122900 extends AbstractMigrationChamilo
 
         if (!$schema->hasTable('resource_link')) {
             $this->addSql(
-                "CREATE TABLE resource_link (id INT AUTO_INCREMENT NOT NULL, resource_node_id INT DEFAULT NULL, c_id INT DEFAULT NULL, session_id INT DEFAULT NULL, usergroup_id INT DEFAULT NULL, group_id INT DEFAULT NULL, user_id INT DEFAULT NULL, visibility INT NOT NULL, start_visibility_at DATETIME DEFAULT NULL COMMENT '(DC2Type:datetime)', end_visibility_at DATETIME DEFAULT NULL COMMENT '(DC2Type:datetime)', display_order INT NOT NULL, resource_type_group INT NOT NULL, created_at DATETIME NOT NULL COMMENT '(DC2Type:datetime)', updated_at DATETIME NOT NULL COMMENT '(DC2Type:datetime)', deleted_at DATETIME DEFAULT NULL COMMENT '(DC2Type:datetime)', INDEX IDX_398C394B1BAD783F (resource_node_id), INDEX IDX_398C394B91D79BD3 (c_id), INDEX IDX_398C394B613FECDF (session_id), INDEX IDX_398C394BD2112630 (usergroup_id), INDEX IDX_398C394BFE54D947 (group_id), INDEX IDX_398C394BA76ED395 (user_id), PRIMARY KEY(id)) DEFAULT CHARACTER SET utf8mb4 COLLATE `utf8mb4_unicode_ci` ENGINE = InnoDB ROW_FORMAT = DYNAMIC;"
+                "CREATE TABLE resource_link (id INT AUTO_INCREMENT NOT NULL, resource_node_id INT DEFAULT NULL, c_id INT DEFAULT NULL, session_id INT DEFAULT NULL, usergroup_id INT DEFAULT NULL, group_id INT DEFAULT NULL, user_id INT DEFAULT NULL, visibility INT NOT NULL, start_visibility_at DATETIME DEFAULT NULL COMMENT '(DC2Type:datetime)', end_visibility_at DATETIME DEFAULT NULL COMMENT '(DC2Type:datetime)', display_order INT NOT NULL, resource_type_group INT NOT NULL, created_at DATETIME NOT NULL COMMENT '(DC2Type:datetime)', updated_at DATETIME NOT NULL COMMENT '(DC2Type:datetime)', deleted_at DATETIME DEFAULT NULL COMMENT '(DC2Type:datetime)', INDEX IDX_398C394B1BAD783F (resource_node_id), INDEX IDX_398C394B91D79BD3 (c_id), INDEX IDX_398C394B613FECDF (session_id), INDEX IDX_398C394BD2112630 (usergroup_id), INDEX IDX_398C394BFE54D947 (group_id), INDEX IDX_398C394BA76ED395 (user_id), INDEX idx_resource_link_sortable_groups (c_id, session_id, usergroup_id, group_id, user_id, resource_type_group), PRIMARY KEY(id)) DEFAULT CHARACTER SET utf8mb4 COLLATE `utf8mb4_unicode_ci` ENGINE = InnoDB ROW_FORMAT = DYNAMIC;"
             );
         }