Allow custom parameters for `InteractiveViewer`

[FaFre]

First of all thank you for the great update @nabil6391 ! I wrote my own implementation of setting the focused node, but with the new update I ditched it all and the new solution works like a charm!

It would be cool tho if it would be possible to initialize the InteractiveViewer with custom parameters to adjust margin, min/max zoom etc.

The parameters are fixed right now: https://github.com/nabil6391/graphview/blob/5fc853cce1c84a2fc4580f8b45c500c49ffe2392/lib/GraphView.dart#L413C14-L421

[nabil6391]

Tell me which params are necessary for you