Test

Add `Product` expression and normalising rules #1290

Job	Run time
Audit (stable)	1m 26s
Audit (nightly)	1m 45s
Test (stable, 2.5.1, ubuntu-latest)	4m 52s
Examples (stable, ubuntu-latest)	1m 41s
Test (stable, 2.5.1, macos-latest)	2m 26s
Examples (stable, macos-latest)	1m 35s
Test (nightly, 2.5.1, ubuntu-latest)	3m 7s
Examples (nightly, ubuntu-latest)	1m 41s
Test (nightly, 2.5.1, macos-latest)	2m 27s
Examples (nightly, macos-latest)	1m 37s
	22m 37s

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