j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/enum/runnableImplementation.kt

@@ -0,0 +1,11 @@
+enum class Color : Runnable {
+    WHITE
+    BLACK
+    RED
+    YELLOW
+    BLUE
+
+    override fun run() {
+        System.out.println("name()=" + name() + ", toString()=" + toString())
+    }
+}