j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/equals/Equals3.java

@@ -0,0 +1,9 @@
+class C{
+    public boolean equals(C c) {
+        return false;
+    }
+
+    boolean foo(C c1, C c2) {
+        return c1.equals(c2)
+    }
+}