Add the ability to enqueue cleaning process

Problem/Motivation

The pagedesigner cleaning process (deletion of the pagedesigner elements tree) is quite expansive and can lead to long processing time when multiple containers are deleted together.

Steps to reproduce

Try to delete a batch of nodes (> 100). The process may takes more than one hour.

Proposed resolution

Give the opportunity to developer to enqueu this process when fitting.

Remaining tasks

User interface changes

API changes

Data model changes