Allow to ask confirmation in custom actions and disable it in batch actions

[javiereguiluz]

Batch actions display a confirmation message in a model windows because they can be "dangerous" (e.g. delete lots of items at once, publish/unpublish lots of items at once, etc.) But some folks prefer to not have that confirmation for some batch actions. Let's add a method to disable this default behavior.

Related to this, custom actions never display a confirmation dialog, but some of those can be destructive or dangerous. So, let's add a method for actions to ask for a confirmation.

While we do this, maybe we can redesign the current behavior based on a sliding down modal and display the message similar to what macOS or Windows do when asking for permission to users.