Show warning when opening the chat tab on a folder
Show warning when opening the chat tab on a folder

This is just a temporary message; in the future the whole tab will be
hidden in that case, but it depends on a fix in server which was not
ready yet for beta 3.

Signed-off-by: Daniel Calviño Sánchez <bd7629e975cc0e00ea7cda4ab6a120f2ee42ac1b@gmail.com>

nextcloud/spreed,nextcloud/spreed,nextcloud/spreed