[FTP] rework creating the root file info
[FTP] rework creating the root file info

There is no need to make the root file info backend specific, as it just
returns a bunch of default values anyway. Also, we want to use the host
display name in there.

xkahn/gvfs-cmis,halfline/gvfs,xkahn/gvfs-cmis,halfline/gvfs,philipl/gvfs,philipl/gvfs,cpatulea/gvfs,philipl/gvfs,thiblahute/gvfs,halfline/gvfs,thiblahute/gvfs,gicmo/gvfs,cpatulea/gvfs,gicmo/gvfs,xkahn/gvfs-cmis,gicmo/gvfs,xkahn/gvfs-cmis,gicmo/gvfs