V1: Structure & upload

This epic will enable to define the generic structure and the upload aspect of a compound document. 

Compound assets are defined as folderish objects representing the parent asset.

We do not currently support drag and drop folder upload from desktop to Web UI. So the only solution we can start with is by having a zip of the compound ready to be uploaded on the server. 

Files must be pre-formatted and made into a .zip which is loaded into the instance. A script in the instance recognizes the file (Material, Indesign, or Product design (3d or other)) and creates the appropriate folderish structure.

This is the way the Presales team and the VF team are handling compound documents in their environment. We can have a look at their studio project to understand their script and how they build the structure.

As an MVP, we can follow this path, but as soon as we support drag and drop, we should think in advance of this method and support a configurator for compound documents. 

Test documents: https://drive.google.com/drive/folders/1WVdHaxOsJyfWp0ZmNN_7sjWFysoMJS5j