j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/equals/Equals4.java

@@ -0,0 +1,5 @@
+class C{
+    boolean foo(String s1, String s2, String s3, String s4) {
+        return s1.equals(s2) == !s3.equals(s4)
+    }
+}