Like a Subscription Request, a Subscription Change Request is used to create a new Open Sale Order,
but, it also archive a previous one at the same time.

The purpose is to change some parameters of an Open Sale Order,
and correctly created compensation movement, to ensure the resource
stock is correct.

Stop using discount resource, and reduce the quantity of the consumed software product / service

Only Sale people can create Subscription Change Request.

TODO: check how quantity precision can be defined

The only use case supported for now is changing an Instance Tree's user.