devcontainer: handle hosts without X11 (#29537)

* Setup xauthority link on host in initializeCommand

* Create a dummy xauthority if it does no exist on host machine

* Remove xauthority line from ci test

.devcontainer/setup_host.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+# setup links to Xauthority
+XAUTHORITY_LINK=".devcontainer/.Xauthority"
+rm -f $XAUTHORITY_LINK
+if [[ -z $XAUTHORITY ]]; then
+    echo "XAUTHORITY not set. Fallback to ~/.Xauthority ..."
+    if ! [[ -f $HOME/.Xauthority ]]; then
+        echo "~/.XAuthority file does not exist. GUI tools may not work properly."
+        touch $XAUTHORITY_LINK # dummy file to satisfy container volume mount
+    else
+        ln -sf $HOME/.Xauthority $XAUTHORITY_LINK
+    fi
+else
+    ln -sf $XAUTHORITY $XAUTHORITY_LINK
+fi