Social Core should not depend on views_bulk_operations

Problem

We've added the ViewsBulkOperationsFormTrait to SocialCoreController. This creates a dependency of social_core on the views_bulk_operations module even though this module isn't necessarily needed at the core of Open Social.

Additionally this mixes reusable logic for VBO users with controller paths that are used by social_core itself.

Solution

Remove the VBO code from SocialCoreController. Either move it into a custom trait and keep the dependency on vbo in social_core or move it to a custom module that other modules can rely on.

The latter option has preference as it makes VBO support optional again.