Agda-stdlib: Change the order of arguments in `Data.List.Relation.Unary.All.cartesianProduct⁺`

[MatthewDaggitt]

The (∀ {x y} → x ∈₁ xs → y ∈₂ ys → P (x , y)) argument should come before the lists xs/ys the proof is being applied to

[gallais]

Doesn't sound well-scoped?

[MatthewDaggitt]

Doh of course. I must have generalised it when porting it from my own library!