`run_system_cached` API will reject systems created by `pipe` and `map`

[benfrankel]

From #14920 (review):

The only maybe issue I can see is that the ZST check won't work for systems created by pipe and map, even when the systems and closures involved are ZSTs. This is due to pipe and map eagerly calling into_system on their receiver, which will result in non-ZST types even when called on ZST types. The solution would be changing them to be lazy and call into_system on their receiver only when into_system is directly called on them.

- @SkiFire13

[alice-i-cecile]

(This will be blocked until the linked PR is merged but I don't want to have to change the labels)