Prepare the devnexus event

As mentionned in https://gitlab.eclipse.org/eclipse-wg/ide-wg/steering-committee/program-plan/-/issues/40#note_2966021, I will attend the devnexus event

This issue is created to prepare this event and more specifically to see what we will be showing on the booth in addition to the standard presentations. Any comment welcome.

• Book flights
• Book hotel
• List demos to be shown
• Prepare initiative 31 (demo, plan, content)