Add Text.Trifecta.Result to Text.Trifecta exports

I can't quite make out whether this was deliberate or an oversight: You haven't exported Text.Trifecta.Result from Text.Trifecta, meaning the `Success` and `Failure` constructors of the Result type are not visible. It broke my compile (when attempting to upgrade from 0.53) so I thought I should mention it. If mere oversight, patch attached. Or was there something else I was supposed to import instead?

AfC