j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/issues/kt-820-field.kt

@@ -0,0 +1,15 @@
+package demo
+
+class Container {
+    var myInt = 1
+}
+
+class One {
+    class object {
+        var myContainer = Container()
+    }
+}
+
+class Test {
+    var b = One.myContainer.myInt.toByte()
+}