Improve management of document sub types

When defining allowed container types or allowed sub types in Studio, sometimes definitions are not consistent, and deployment order matters so result could be surprising

E.g: I've added the already created "Custom Folder 1" as a possible parent of my new "Custom folderish 1" document type. But i didn't added "Custom folderish 1" document type as a possible child of "Custom Folder 1".

=> better manage deps (by adding, at build time, container and sub types resolving dependencies) or issue a validation error to force user to make these definitions consistent