Harden UUID validation in ComponentTreeStructureConstraintValidator

Picking this up and giving my best try.

The MR is ready for review.

Thanks @abhisekmazumdar!

@tedbow Thoughts on all the test-only UUIDs that now cause failures, such as

+    'tree[uuid-in-root][the_body][0][uuid]' => 'The UUID "<em class="placeholder">uuid-level-1</em>" is not a valid UUID.'
+    'tree[uuid-level-2][the_body][0][uuid]' => 'The UUID "<em class="placeholder">uuid-level-3</em>" is not a valid UUID.'
+    'tree[uuid-level-2][the_body][1][uuid]' => 'The UUID "<em class="placeholder">uuid-last-in-tree</em>" is not a valid UUID.'
+    'tree[uuid-level-1][the_body][0][uuid]' => 'The UUID "<em class="placeholder">uuid-level-2</em>" is not a valid UUID.'

?

LGTM! Well done, @abhisekmazumdar 😊 That looks as simple/elegant as I'd hoped 😄

#3472299: Update default config to make a fresh install result in an XB UI with an empty canvas will change/reduce the amount of test expectations that need to be updated, so postponing this on that.

Can we resume work on this ?

Yes! Great catch! Thanks, @abhisekmazumdar :)

Didn't happen at Barcelona, but let's get it on https://contribkanban.com/board/experience_builder now 😄

Given the huge range of tests that would need updating by now, I don't think this is Novice anymore.

It's something that might be a stable blocker. Doing it now doesn't buy us much though, so postponing.

It looks like #3468272: Store the ComponentTreeStructure field property one row per component instance will largely do this!

Reviewing #3468272: Store the ComponentTreeStructure field property one row per component instance right now, it 100% certainly addresses this! 🥳