j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/constructors/fieldsInitializedFromParams9.java

@@ -0,0 +1,11 @@
+class C {
+    private final String string;
+
+    public C(String s, int a) {
+        this.string = s;
+    }
+
+    public C(String s) {
+        this(s, s.length());
+    }
+}