Add a gizmo-based overlay to show UI node outlines #31928

Job	Run time
ci	6m 12s
check-doc	7m 21s
build (windows-latest)	9m 14s
check-missing-examples-in-docs	31s
build (ubuntu-latest)	4m 31s
miri	10m 38s
run-examples-on-windows-dx12	17m 9s
build (macos-latest)	6m 40s
check-bevy-internal-imports	6s
check-missing-features-in-docs	2m 43s
markdownlint	1m 11s
check-compiles	3m 50s
msrv	2m 31s
build-wasm	1m 11s
	1h 13m 48s

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