Wrong interface languague in Collabora online

[florencebiree]

Using recent version of Collabora online, the ui= parameter given to the wopi endpoint is no longer respected, and Collabora interface is now in english by default (instead of French in my case). Nextcloud use the lang= parameter instead, and it's work (for the same Collabora endpoint).

Changing this line in the wopi utils file to change ui= by lang= make it work.

I don't know if the lang= parameter works also with other office suite, but I think it must be given for Collabora instead of ui=.