Simplify const rendering

Author: ghostbuster91

Diff for: compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -784,8 +784,7 @@ object SpaceEngine {
 
     def doShow(s: Space, flattenList: Boolean = false): String = s match {
       case Empty => "empty"
-      case Typ(ConstantType(const : Constant), _) if const.tag == StringTag => "\"" + const.value + "\""
-      case Typ(ConstantType(const : Constant), _) => "" + const.value 
+      case Typ(c: ConstantType, _) => c.value.show
       case Typ(tp: TermRef, _) =>
         if (flattenList && tp <:< defn.NilType) ""
         else tp.symbol.showName