Add support for recursive cloning

This is a follow-up to #2706639: Support for sub-entity cloning. While we can now clone entities within entities, the functionality won't work recursively (i.e. all the way down if there are multiple levels of nesting). We need to add support for this.

Subtasks:

• Allow entity_reference_revisions fields to be cloned recursively.
• Improve the UX/UI for the recursive clone form.