Add Version command

Author: lwronski

modules/cli/src/main/scala/scala/cli/commands/Version.scala

@@ -0,0 +1,12 @@
+package scala.cli.commands
+
+import caseapp._
+
+import scala.build.internal.Constants
+
+object Version extends ScalaCommand[VersionOptions] {
+  override def group = "Miscellaneous"
+  def run(options: VersionOptions, args: RemainingArgs): Unit = {
+    println(Constants.version)
+  }
+}

modules/cli/src/main/scala/scala/cli/commands/VersionOptions.scala

@@ -0,0 +1,11 @@
+package scala.cli.commands
+
+import caseapp._
+
+@HelpMessage("Print scala-cli version")
+final case class VersionOptions()
+
+object VersionOptions {
+  implicit val parser = Parser[VersionOptions]
+  implicit val help   = Help[VersionOptions]
+}