Add a minimal migration script from Social Collab to Nuxeo CAP

A first step could be:

News => Note
Article => Note
SocialDomain => Domain
SocialFolder => Folder
SocialWorkspace => Workspace (but we need to remove also the specific social workspace ACLs...)

But what about the no more used schemas? They will still be in the DB and we may need to clean them also.

We probably want to also delete all documents of type SocialSection, NewsItemsRoot and DashboardSpacesContainer (no use outside of Social Workspace).