Fix svg icons disapearing in app navigation when text overflows
Fix svg icons disapearing in app navigation when text overflows

The issue is caused by the icon being positionned with negative margins
and the `overflow: hidden` rule when hide the icon when the text
overflows. Remove positioning with negative margins. This was only
happening in Firefox.

This fix #23849

Signed-off-by: Carl Schwan <de187642e6c75f60d10f29e52cab54cdf676870d@carlschwan.eu>

nextcloud/server,nextcloud/server,nextcloud/server,nextcloud/server