Autosave PoC

This is very rough indeed but works as a proof of concept.

In the UI you can now click the Publish button and it posts the current layout and model to the server. This is saved in the shared tempstore keyed by entity type and ID. When you navigate away from the XB UI and come back to the same node, the saved layout and model are reloaded, instead of always getting the default dummy layout.

@longwave Can you add a GIF for #3? 🤓

Demo GIF:

Looking good! 🏓 Basically only nitpicky concerns that all relate to setting the right expectations: this is temporary, it will change, and the first follow-up step is to update the end-to-end tests that must be linked.

@wim leers thanks for the review, back to you

• Thanks for the follow-up!
• Love the name you picked 🤣

Needs work because:

1. Tests are failing now 😅
2. Last concern: let's please make the trait link to an issue where this will be fleshed out more — even if it's just a meta issue.

Pre-emptively approved already — I trust you to address those last bits 👍

@wim leers ok!

Addressed the last bits. If tests pass I will merge

🚢 Ship it!

🎉

Automatically closed - issue fixed for 2 weeks with no activity.