moment not loading locales

While tackling ELEMENTS-1182 we've found out that moment only have en locale loaded.
This will lead that widgets as nuxeo-date-picker that rely on moment locale data will be broken.

An easy way to reproduce the issue is to set the browser's language to french.
Then we can see that almost all the UI is translated but, as soon as we expand nuxeo-date-picker to see the calendar we can check that everything is in english. Also, the first day of the calendar will be Sunday but, in french, it should be Monday (Lundi).