Remove hardcoded context path in Nuxeo Spreadsheet editor js files

The context path is hardcoded in with /nuxeo in Spreadsheet editor javascript files, for example at

https://github.com/nuxeo/nuxeo/blob/654f687f79e5a85bb29a83913f3e3d8e539176b3/addons/nuxeo-platform-spreadsheet/nuxeo-platform-spreadsheet-web/src/main/js/app/nuxeo/connection.js#L23

https://github.com/nuxeo/nuxeo/blob/10.10/addons/nuxeo-platform-spreadsheet/nuxeo-platform-spreadsheet-web/src/main/js/app/app.js#L89

 https://github.com/nuxeo/nuxeo/blob/10.10/addons/nuxeo-platform-spreadsheet/nuxeo-platform-spreadsheet-web/src/main/js/app/app.js#L191