qtxdg-desktop-file-start: Handle relative paths
qtxdg-desktop-file-start: Handle relative paths

XdgDesktopFile::load() takes absolute and relative paths. This utility command
should too.
Also there's no need to convert the user provided file path to canonical,
XdgDesktopFile::load() already does that.

lxde/libqtxdg,lxde/libqtxdg,libqtxdg/libqtxdg,libqtxdg/libqtxdg