j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/newClassExpression/newAnonymousClass.java

@@ -0,0 +1,7 @@
+//expression
+new Runnable() {
+  @Override
+  public void run() {
+    System.out.println("Run");
+  }
+};