streamFromString

This function would be nice to have.

```purescript
streamFromString :: forall w. String -> Effect (Node.Readable w)
```

https://github.com/purescript-contrib/pulp/blob/78f7aa6ae76337ea6f8362cac03fb1c8ee1858cd/src/Pulp/System/Stream.purs#L66
