Version 0.0.2: Update Example App with an example UndirectedGraph

[ToluAta]

The example app is lacking examples.

The task would be to put in a button with the Label Create a UndirectedGraph in main.dart.
On press a new view would be opened with a form to fill in the needed fields with a ListView below it.
The form should fill the ListView.
The List should show the ids of the nodes and on click (e.g. expansion panel) should show all of the nodes values.

This issue is part of #4