j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/constructors/nestedClassNameInParameterDefaults.kt

@@ -0,0 +1,9 @@
+class A(nested: A.Nested = A.Nested(A.Nested.FIELD)) {
+
+    class Nested(p: Int) {
+        class object {
+
+            public val FIELD: Int = 0
+        }
+    }
+}