j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/identifier/finalFieldReference.kt

@@ -0,0 +1,10 @@
+class `$$$$$`
+
+open class `$`
+
+class `$$`(val `$$$`: `$$$$$`) : `$`() {
+
+    public fun `$$$$$$`(): `$$$$$` {
+        return `$$$`
+    }
+}