xdg-open and xdg-email reimplementation for containerized apps

 Applications running in a Flatpak sandbox cannot normally launch arbitrary
 subprocesses outside the container to open files and URLs. This
 package provides reimplementations of the standard xdg-open(1) and
 xdg-email(1) command-line tools intended to be run inside the container.
 They use the D-Bus session bus to communicate with the xdg-desktop-portal
 service outside the container.
 .
 To avoid conflicting with the standard xdg-utils package, these tools
 are installed in /usr/libexec/flatpak-xdg-utils. This directory can be
 added to the PATH when preparing a container, or used as a target for
 container-specific symbolic links in /usr/bin.
 .
 This package also contains flatpak-spawn, which can be used by Flatpak
 applications to launch processes outside the container. Unprivileged
 applications can use this mechanism to launch a helper tool such as a
 thumbnailer in a version of their sandbox with more restrictive
 permissions, and specially-privileged applications with the 'devel' flag
 (such as GNOME Builder) can use this mechanism to bypass the sandbox and
 run commands on the host system.
 .
 This package is normally only useful if you are using Debian packages to
 construct a Flatpak runtime or a similar container, and should not be
 installed on a normal Debian desktop system. On desktop systems please
 install the reference implementation of the xdg-open and xdg-email tools,
 which can be found in the xdg-utils package.
 .
 If this package is installed in a non-Flatpak environment for testing,
 it will require the dbus-session-bus and xdg-desktop-portal packages
 (which would not be useful to install in a container).