j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/callChainExpression/libraryMethodCallFromInstance.kt

@@ -0,0 +1,19 @@
+class Library {
+    fun call() {
+    }
+
+    fun getString(): String {
+        return ""
+    }
+}
+
+class User {
+    fun main() {
+        val lib = Library()
+        lib.call()
+        lib.getString().isEmpty()
+
+        Library().call()
+        Library().getString().isEmpty()
+    }
+}