Introduce AspectRatio struct #31855

Job	Run time
check-missing-examples-in-docs	30s
build (windows-latest)	3m 33s
check-bevy-internal-imports	5s
check-doc	5m 6s
build (ubuntu-latest)	3m 15s
ci	2m 10s
build (macos-latest)	2m 21s
miri	5m 59s
run-examples-on-windows-dx12	20m 19s
check-missing-features-in-docs	50s
markdownlint	1m 23s
check-compiles	3m 21s
build-wasm	52s
msrv	58s
	50m 42s

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