j2k: flatten test cases and testData directory structure

Move j2k/test/tests -> j2k/tests, j2k/test/testData -> j2k/testData

j2k/testData/fileOrElement/switch/emptySwitch.kt

@@ -0,0 +1,15 @@
+public class NonDefault {
+    class object {
+        public fun main(args: Array<String>) {
+
+            val value = 3
+            val valueString = ""
+            when (value) {
+
+            }
+            System.out.println(valueString)
+        }
+    }
+}
+
+fun main(args: Array<String>) = NonDefault.main(args)