devcontainer: expose host config, fix mac screen issues (#29932)

* export host config via .host/.env file. fix mac display issues

* append instead of replace for bashrc

* Log when mac display override happens

* Update xauthority path in json

.devcontainer/host_setup.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+# setup .host dir
+mkdir -p .devcontainer/.host
+
+# setup links to Xauthority
+XAUTHORITY_LINK=".devcontainer/.host/.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 $XAUTHORITY_LINK
+fi
+
+# setup host env file
+HOST_INFO_FILE=".devcontainer/.host/.env"
+SYSTEM=$(uname -s | tr '[:upper:]' '[:lower:]')
+echo "HOST_OS=\"$SYSTEM\"" > $HOST_INFO_FILE