feat: add -h to alternatives for -help

I've tried this no less than 3 times over the weekend and it annoys me
every time I get the `bad option '-h' was ignored` and it brings me
into the REPL. I think it's always a good idea to just default
`-help|--help|-h` all to help. Since this doesn't seem to conflict with
anything this just adds it in.

Author: ckipp01

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -101,7 +101,7 @@ trait CommonScalaSettings:
   val color: Setting[String] = ChoiceSetting("-color", "mode", "Colored output", List("always", "never"/*, "auto"*/), "always"/* "auto"*/, aliases = List("--color"))
   val verbose: Setting[Boolean] = BooleanSetting("-verbose", "Output messages about what the compiler is doing.", aliases = List("--verbose"))
   val version: Setting[Boolean] = BooleanSetting("-version", "Print product version and exit.", aliases = List("--version"))
-  val help: Setting[Boolean] = BooleanSetting("-help", "Print a synopsis of standard options.", aliases = List("--help"))
+  val help: Setting[Boolean] = BooleanSetting("-help", "Print a synopsis of standard options.", aliases = List("--help", "-h"))
   val pageWidth: Setting[Int] = IntSetting("-pagewidth", "Set page width", ScalaSettings.defaultPageWidth, aliases = List("--page-width"))
   val silentWarnings: Setting[Boolean] = BooleanSetting("-nowarn", "Silence all warnings.", aliases = List("--no-warnings"))