Visualisation dashboard

[benedikt-voelkel]

We could think about a handy visualisation dashboard in the browser. Already, optuna by default relies on plotly for visualisations which yields quite interactive plots.
We could think about a mechanism to load them e.g. via a notebook.
So having a notebook that reads in and displays the performance and evaluation plots could be extremely useful for the user to have get a comprehensive overview of the optimisation.

[benedikt-voelkel]

We should explore https://github.com/optuna/optuna-dashboard a bit but there seems to be no need of implementing anything like this ourselves