Describe the bug

After the #15002 there seems to be a bug when the notification is an attachment.

Since now the cell checks if the user can participate in that resource, that asks the attachment model for a method that does not exist.

    def show
      if !notification.can_participate?(current_user)
        render :not_available
      elsif notification.deleted_resource?
        render :deleted
      elsif notification.hidden_resource?
        render :moderated
      else
        render :show
      end
    end

This has caused problems with other models, such as in this pr #15830

To Reproduce

1. Upload an attachment to a process with one admin user
2. Go to the notifications of a second admin user
3. See it crash

Expected behavior

You can access the notification landing and see the notifications of type Decidim::Attachment

Screenshots

No response

Stacktrace

Cause: NoMethodError: undefined method can_participate?' for an instance of Decidim::Attachment /usr/local/bundle/gems/activemodel-7.2.3/lib/active_model/attribute_methods.rb:512:in method_missing'
/usr/local/bundle/gems/activerecord-7.2.3/lib/active_record/attribute_methods.rb:495:in method_missing' /usr/local/bundle/bundler/gems/decidim-e3f6fc3ac643/decidim-core/app/models/decidim/notification.rb:41:in can_participate?'
/usr/local/lib/ruby/3.3.0/delegate.rb:87:in method_missing' /usr/local/bundle/bundler/gems/decidim-e3f6fc3ac643/decidim-core/app/cells/decidim/notification_cell.rb:10:in show'

Extra data

• Decidim Version: 0.31 (release branch)
• Decidim installation: Participa Navarra

Additional context

No response