Add differential testing harness #426

Job	Run time
Test (windows-2022, x86_64-pc-windows-msvc)	1m 13s
cargo-deny	57s
Test (ubuntu-24.04, x86_64-unknown-linux-gnu)	1m 21s
Test (macOS-latest, x86_64-apple-darwin)	1m 23s
Lint	1m 22s
Test (ubuntu-24.04, aarch64-linux-android, x86_64-unknown-linux-gnu)	1m 17s
test_success	1s
	7m 34s

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