Add support of OnlyOffice document (as ziplike file)

Originaly, the y format (docy, xlsy, ppty) is a file extension that is use by an OnlyOffice document.

An OnlyOffice document is composed by :

• a file with extension in (docy, xlsy, ppty)
• a separate media folder containing media files (Ex: media/image1.png)

Several problems :

• Two documents cannot be in the same folder
• How to send / get from Cloudooo to ERP5 ?
• The document cannot be stored easily in ERP5 (embedded files ? seperate images linked to the document by predecessors ??)
• How to download an OnlyOffice document from ERP5 ? How to load it on OfficeJS ?

To solve, we embbed all the files composing the document into one zip (like docx, odt, ...) :

• Two documents can be in the same folder
• We send / get from Cloudooo as usual with portal transform
• The document can be stored in File data in ERP5 like any other docx document.
• document.getData allows to download the document data and JSZip can be used to extract easily the body in OfficeJS.

To keep backward compatibility, a docy can be :

• the OnlyOffice document body (startsWith("DOCY;v2;"))
• can be a zip file (startsWith("PK\x03\x04")) containing one file at the root of the archive + optional media folder