Add differential testing harness #430

Job	Run time
Lint	5m 48s
cargo-deny	53s
Test (ubuntu-24.04, x86_64-unknown-linux-gnu)	21m 36s
Test (windows-2022, x86_64-pc-windows-msvc)	35m 40s
Test (ubuntu-24.04, aarch64-linux-android, x86_64-unknown-linux-gnu)	9m 27s
Test (macOS-latest, x86_64-apple-darwin)	20m 18s
test_success	2s
	1h 33m 44s

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