Fix position of local container children in older Firefox versions
Fix position of local container children in older Firefox versions

In older Firefox versions (like Firefox 47, the one used to run the
acceptance tests), when there are one or two participants in the call,
the video, avatar and media indicators of the local container appear
centered on the right edge of the app content wrapper. With more
participants in the call their position is the expected one.

Calls with one or two participants use a special layout to make the
local video larger, and in that case the local container children use an
absolute position which is relative to the app content wrapper (due to
the container also using an absolute position in that case instead of a
relative position like done when there are more participants).

For some reason (maybe related to the app content wrapper being a flex
box) their position is not properly calculated, so their alignment to
the right edge of the app content wrapper must be forced by setting
"right: 0" (which does not interfere with the layout in newer versions).

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

nextcloud/spreed,nextcloud/spreed,nextcloud/spreed