This module defines tensor products, which are later used to define
the concept of profunctor strength. The two primary tensor products
in `Idr` are the product (`Pair`) and the coproduct (`Either`).
This module defines endofunctors in the category of profunctors `[Idrᵒᵖ * Idr, Idr]`,
along with adjunctions of those functors.
Examples of these functors include `Yoneda`, `Pastro`, `Closure`, etc.