run: Allow remapping Xauthority entries for remote or forwarded X11
run: Allow remapping Xauthority entries for remote or forwarded X11

As with non-path-based AF_UNIX sockets, both of these are going to
require --share=network to be enabled, so print a warning if it isn't.
We don't automatically enable --share=network, because that elevates
the privileges of apps that would otherwise have entered a new network
namespace, but regular users of remote X11 can choose to enable it with
`flatpak run --share=network` or `flatpak override --share=network`.

Resolves: https://github.com/flatpak/flatpak/issues/397
Signed-off-by: Simon McVittie <0e1aea601907c1a85c2dc96e5ea37e23c58d2e9b@collabora.com>

flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak