erp5_officejs: add spreadsheet gadget

Creating a renderjs gadget that follows a standard interface to get, edit and save spreadsheet document using jio. Spreadsheet gadget is based on onlyOffice editor.

Format of spreadsheet document that can be edited in renderjs gadget is xlsy. At present the spreadsheet document conversion from any (xlsx, ods, etc) to xlsy is done automatically during first synchronization with gadget by cloudooo.