META: Conflict free concurrent editing

I think this is a stable blocker because at present we have data loss.

@larowlan re #2 about this being a stable blocker

I agree we should not data loss if 2 users are editing the same entity but I wonder if our goal should be to support this workflow in 1.0 or just prevent it from happening. Just technically supporting doesn't seem like enough, we should have good UX around it and if we can't achieve that it seems like it would better to not support it all.

AFAICT ✨ Implement time travel (undo/redo/revert) of auto-saved states across devices and users Active is related?

I updated the summary to acknowledge the for beta1 we are not supporting concurrent editing.

Also added 🐛 Add rudimentary conflict prevention to the Config Auto-save end-point Active as a child because we have to do this for config entities too

🐛 Click publish shortly after making a change can lead to error Active should be linked from here per @tedbow's comment at #3520592-13: Clicking publish shortly after making a change can lead to an error → , which ties it to 📌 [PP-1] Enforce conflict enforcement outside of tests and e2e tests Postponed .

I think to 2 child issues that would get us closer to concurrent editing are
📌 [PP-1] For less conflict errors only validate region auto-save on layout PATCH Postponed

📌 Replace the postPreview action with atomic equivalents Active

I am not sure how much work 3492065 would be but 3532056 is small change and just now needs test coverage.

3532056 will not get use all the way to concurrent editing but at least it would mean that if you were editing a component in 1 region you would not error if there were any changes to any other region. I think practically this would cause there to be many fewer conflicts

We have a MVP solution in place which gets us to stable.