Instead, pass the untranslated message as polkit.message and set the
gettext domain on polkit.gettext_domain. For printf()-style messages,
occurences of the form $(name_of_key) in the translated version of
polkit.message are expanded with the value of the property
name_of_key. See the pkexec(1) mechanism for an example of how to use
this.

Additionally, the property polkit.icon_name can be set to the
icon. Note that not all authentication agents use this - in
particular, gnome-shell does not.

It is no longer possible to set the details to be shown in the
authentication dialog. It was never a good idea to hide information
there anyway. Instead, the mechanism should format a meaningful
message.

Signed-off-by: David Zeuthen <davidz@redhat.com>