Java to Kotlin converter: refactoring and fixing switch conversion

#KT-5390 Fixed

j2k/tests/testData/ast/switch/invalidSwitch.java

@@ -0,0 +1,7 @@
+//method
+void foo() {
+  switch(a) {
+    System.out.println("1")
+    System.out.println("2")
+  }
+}