bug fix: for cdrs page, failed request when submit visible columns

[Ivanov-Anton]

Description

added the json download links for CDR admin index page because the ActiveAdmin has build in
condition see below:

def restrict_format_access!
  unless request.format.html?
    presenter = active_admin_config.get_page_presenter(:index)
    download_formats = (presenter || {}).fetch(:download_links, active_admin_config.namespace.download_links)
    unless build_download_formats(download_formats).include?(request.format.symbol)
      raise ActiveAdmin::AccessDenied.new(current_active_admin_user, :index)
    end
  end
end

so download_formats it is actually download_links from index page

Additional links

closes #1363