j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/inheritance/classOneExtendsBaseWithOneParam.java

@@ -0,0 +1,10 @@
+//file
+class Base {
+  Base(String name) {}
+}
+
+class One extends Base {
+  One(String name, String second) {
+    super(name)
+  }
+}