Use Natural Transformations wherever possible

[milesfrain]

This change makes the type signatures of NonEmptyArray functions more consistent with the other container types.

Here's an example of the previous inconsistencies: https://pursuit.purescript.org/search?q=toUnfoldable

[hdgarrood]

FWIW this is something that we explicitly decided against previously. There will be discussion on a closed issue or PR in this repo or potentially one of the other core library repos.

[hdgarrood]

I wasn't aware that the lists library uses the ~> type synonym. I agree that these should be consistent, but I think we should change the lists library to remove uses of ~> rather than adding them here.

[JordanMartinez]

I agree that these should be consistent, but I think we should change the lists library to remove uses of ~> rather than adding them here.

I agree with this, too. It avoids the issue of confusion that can arise if someone doesn't know what ~> is.