Update Scala Coding Style guideline for scalafmt

[imback82]

Update https://github.com/microsoft/hyperspace/blob/master/docs/coding-guidelines/scala-coding-style.md on how to set up scalafmt in IDE so that contributors get consistent result.

[sezruby]

@paryoja Could you update the documentation for IntelliJ/scalafmt? while you're setting up it :)