Add help parameter to print specific options for ScalaNative and Scal…

[lwronski]

…aJs groups

By default, options for ScalaJs and ScalaNative will be hidden. These options will be displayed if someone explicitly pass --help-js or --help-native to options.

I added a new hiddenGroups parameter in HelpFormat to hide all parameters from selected groups by default:

ScalaComand.scala
...
.withHiddenGroups(Some(Seq(
         "Scala.JS",
         "Scala Native"
       )))

and then, to display for example options for ScalaJs, it is required to specify --help-js.
Printing options for ScalaJS is handled in HelpGroupOptions.scala. Before printing help, I will remove the ScalaJS from the sequence of hidden groups in HelpFormat.