j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/class/abstractClass.java

@@ -0,0 +1,8 @@
+//class
+abstract class A { 
+  abstract void callme();
+
+  void callmetoo() {
+    print("This is a concrete method.");
+  }
+}