enhancement - Make image build process use temporary volume to proceed

[MetaBarj0]

carrier image creation process was born at the early stage of carrier. It has been incorporated 'as-is' in the unique carrier script without thinking about performances (though it has been refactored for readability and testability purposes).
Today, while being created, an image use the overlay storage of its running container as temporary staging area.
The factorization feature opened the way to re-think existing image operations like the image creation.
After being implemented, an image being created won't use the overlay storage of its running container to build up. It should lead to a significant performance boost in image creations.