j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/callChainExpression/libraryMethodCall.kt

@@ -0,0 +1,17 @@
+class Library {
+    class object {
+        fun call() {
+        }
+
+        fun getString(): String {
+            return ""
+        }
+    }
+}
+
+class User {
+    fun main() {
+        Library.call()
+        Library.getString().isEmpty()
+    }
+}