Rewrite `MultiProduct` #664

Job	Run time
check format	14s
msrv	37s
check	15s
test	54s
check (--no-default-features)	11s
check (--no-default-features --features use_alloc)	11s
check (--all-targets --all-features)	26s
All checks succeeded	1s
	2m 49s

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