MonadThrow and MonadCatch instances would be handy

[dalaing]

I'm trying to integrate WebDriver-w3c with hedgehog - in particular, the state machine based testing - and it looks like I'd need instance of MonadThrow and MonadCatch from exceptions in order to do this.

I can probably put together a PR myself, for both webdriver-w3c and script-monad, adding something like: instance (MonadThrow eff, Monad (t eff), MonadTrans t) => MonadThrow (WebDriverTT t eff) but I wanted to check if you'd be interested in that PR (and the dependency on exceptions that it brings).