Add OpenBao extension to Docker build extension mapping

This adds the OpenBao vault extension to the Docker extension mapping
script, ensuring it is properly integrated into Docker images and
accessible via the OPENBAO_ environment variable prefix.

Author: subbareddyalamur1

guacamole-docker/build.d/010-map-guacamole-extensions.sh

@@ -115,5 +115,6 @@ map_extensions <<'EOF'
     guacamole-display-statistics................DISPLAY_STATISTICS_
     guacamole-history-recording-storage.........RECORDING_
     guacamole-vault/ksm.........................KSM_
+    guacamole-vault/openbao.....................OPENBAO_
 EOF