Add differential testing harness #384

Job	Run time
Lint	5m 28s
Test (ubuntu-24.04, x86_64-unknown-linux-gnu)	22m 24s
cargo-deny	1m 22s
Test (macOS-latest, x86_64-apple-darwin)	18m 2s
Test (windows-2022, x86_64-pc-windows-msvc)	42m 30s
Test (ubuntu-24.04, aarch64-linux-android, x86_64-unknown-linux-gnu)	8m 4s
test_success	3s
	1h 37m 53s

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