Add visualizer for QQmlJSScope

Since QQmlJSScope hierarchies are fairly complicated, some way to dump them into a file and visualize would be very beneficial for debugging purposes.

One approach (and perhaps the most popular) would be to use graphviz [1] (e.g. DOT format [2]).

What info is probably interesting (each graph node is a QQmlJSScope?):

• internalName() and baseTypeName()
• file name (albeit not extremely useful)
• own properties (property name, type name, attributes?)
• own methods
• enums
• js identifiers?
• ...

[1]: https://www.graphviz.org/about/
[2]: https://www.graphviz.org/doc/info/lang.html