Ensure scene id props exist

[bkrmendy]

Problem

We link threads to scenes by adding the value of a scene's id prop to the thread metadata. If a scene doesn't have an id prop, we won't be able to link comments to it. Not all scenes may have an id prop, so we need a mechanism that adds the id prop to scenes without it.

Fix

Walk the contents tree after each dispatch, and ensure that all scenes have ids and their values are all unique. If a scene doesn't have an id prop, or another scene already uses it, it's overwritten by the scene's uid.

[github-actions]

Try me

[relativeci]

Job #10035: Bundle Size — 59.81MiB (-4.08%).

621ec87(current) vs 8f5e3ac master#10018(baseline)

Warning

Bundle contains 66 duplicate packages – View duplicate packages

Bundle metrics   7 changes 2 regressions 1 improvement

	Current Job #10035	Baseline Job #10018
Initial JS	45.62MiB(+0.17%)	45.55MiB
Initial CSS	0B	0B
Cache Invalidation	53.51%	19.9%
Chunks	27(+3.85%)	26
Assets	31(+3.33%)	30
Modules	4499(+2.41%)	4393
Duplicate Modules	580(+22.36%)	474
Duplicate Code	27.54%(-10.41%)	30.74%
Packages	462	462
Duplicate Packages	65	65

Bundle size by type   2 changes 1 regression 1 improvement

	Current Job #10035	Baseline Job #10018
JS	59.8MiB (-4.08%)	62.34MiB
HTML	11.87KiB (+2.85%)	11.54KiB

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View job #10035 report View fix/check-scene-id-prop branch activity View project dashboard

[github-actions]

Performance test results:

[ruggi]

I would put the IS_TEST_ENVIRONMENT as the first clause in the function, to make it clear it's a separate thing