j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/function/varVararg.java

@@ -0,0 +1,8 @@
+//file
+package demo;
+
+class Test {
+  void test(Object ... args) {
+    args = new Integer[] {1, 2, 3};
+  }
+}