[Refactoring] Add refactoring action to move type members to extension (#12795)

This implements SR-6297.

tools/SourceKit/lib/SwiftLang/SwiftSourceDocInfo.cpp

@@ -1515,6 +1515,7 @@ static void resolveRange(SwiftLangSupport &Lang,
         return;
       }
       case RangeKind::SingleDecl:
+      case RangeKind::MultiTypeMemberDecl:
       case RangeKind::MultiStatement:
       case RangeKind::SingleStatement: {
         Receiver(Result);