Implement lightmaps. #34121

Job	Run time
check-bevy-internal-imports	4s
build (windows-latest)	8m 4s
check-doc	6m 46s
build (ubuntu-latest)	2m 59s
check-missing-examples-in-docs	33s
build (macos-latest)	6m 19s
ci	3m 0s
miri	7m 18s
run-examples-on-windows-dx12	15m 49s
toml	4s
check-missing-features-in-docs	32s
markdownlint	1m 18s
check-compiles	4m 3s
msrv	1m 46s
build-wasm	1m 20s
	59m 55s

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