qubes.ShowInTerminal needs a graphical session running

This specifically fixes qvm-console-dispvm tool, which uses
qubes.ShowInTerminal to show the actual console. This service uses
xterm, so it needs X session running already.

Fixes QubesOS/qubes-issues#5805

debian/qubes-core-agent.install

@@ -44,6 +44,7 @@ etc/qubes/rpc-config/qubes.OpenInVM
 etc/qubes/rpc-config/qubes.OpenURL
 etc/qubes/rpc-config/qubes.SelectFile
 etc/qubes/rpc-config/qubes.SelectDirectory
+etc/qubes/rpc-config/qubes.ShowInTerminal
 etc/qubes/rpc-config/qubes.StartApp
 etc/qubes/rpc-config/qubes.InstallUpdatesGUI
 etc/qubes/rpc-config/qubes.VMShell+WaitForSession

qubes-rpc/qubes.ShowInTerminal.config

@@ -0,0 +1 @@
+wait-for-session=1

rpm_spec/core-agent.spec.in

@@ -602,6 +602,7 @@ rm -f %{name}-%{version}
 %config(noreplace) /etc/qubes/rpc-config/qubes.OpenURL
 %config(noreplace) /etc/qubes/rpc-config/qubes.SelectFile
 %config(noreplace) /etc/qubes/rpc-config/qubes.SelectDirectory
+%config(noreplace) /etc/qubes/rpc-config/qubes.ShowInTerminal
 %config(noreplace) /etc/qubes/rpc-config/qubes.StartApp
 %config(noreplace) /etc/qubes/rpc-config/qubes.InstallUpdatesGUI
 %config(noreplace) /etc/qubes/rpc-config/qubes.VMShell+WaitForSession