Add organization_id field to Groups finder

Instead of creating Organization specific groups finder we should just extend the standard groups finder with an organization_id parameter.

1. Extend the standard groups finder with organization_id parameter
2. Modify the organization group resolver to use the standard group finder instead of the organization-specific group finder
3. Remove the organization-specific group finder
4. Finally, extend the organization groups resolver to accept an id field and pass through to the standard group finder