Pipes factored out + EnvIO.FromToken + Applicative Zip

[louthy]

The Pipes functionality that is based on the Haskell Pipes library has been factored out to its own library: LanguageExt.Pipes. This is so I can add more functionality to it (based on the supplementary libraries in the Haskell ecosystem). It also creates a clear demarcation: stating that it's not an 'essential'. I think this makes sense because Pipes is quite advanced and currently not the easiest thing to use for those new to FP in C#.

I have also added EnvIO.FromToken, which allows you to construct an EnvIO that subscribes to the token provided. This is useful if you need to use IO within an existing async workflow, rather than at the edge. -- as I was writing this, I realised there was a better way using the existing EnvIO.New, so this has gone already!

The various bespoke zip functions and extensions have now been generalised to work with any applicative. So zips all round!

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This discussion was created from the release Pipes factored out + EnvIO.FromToken + Applicative Zip.