support for chained sideInput and sideOutput

[hlagosp]

I have a use case where we need to produce multiple outputs using a sideInput however it looks like this is not supported in https://github.com/spotify/scio/blob/main/scio-core/src/main/scala/com/spotify/scio/values/SCollectionWithSideInput.scala. I was wondering if there is any workaround for this.

thanks Hector