lib/remote: Add the URL to the remote when creating it from ostree
lib/remote: Add the URL to the remote when creating it from ostree

Since we can now get the URL of the remote directly from the
OstreeRemote object, we should use it when creating a FlatpakRemote.

This will allow temporary FlatpakRemote objects (corresponding to
removable mounts) to have a URL set to them.

Closes: #1587
Approved by: mwleeds

flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak