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.java

@@ -0,0 +1,14 @@
+//file
+package demo;
+
+class Container {
+  int myInt = 1;
+}
+
+class One {
+  static Container myContainer = new Container();
+}
+
+class Test {
+  byte b = One.myContainer.myInt;
+}