Add differential testing harness #429

Job	Run time
Lint	5m 6s
Test (macOS-latest, x86_64-apple-darwin)	8m 18s
Test (ubuntu-24.04, x86_64-unknown-linux-gnu)	8m 14s
Test (ubuntu-24.04, aarch64-linux-android, x86_64-unknown-linux-gnu)	8m 15s
Test (windows-2022, x86_64-pc-windows-msvc)	7m 59s
cargo-deny	58s
test_success	1s
	38m 51s

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