[WORKFLOW] Streamline plotting methods

[amanmajid]

Description

The current workflow relies on a number of plotting libraries (e.g., matplotlib, basemap, plotly, seaborn etc.). This results in bloating of environments, which can give rise to conflicts. In addition, we shouldn't rely on matplotlib for geospatial visualisations given that there are much better solutions to do this.

I would therefore suggest we streamline plotting methods to use ONE library. Since most of our plots are currently made with plotly, we could just use that.

I think this mainly affects three functions in workflow/visualisations.py:

• plot_transmission_capacity()
• plot_transmission_flow()
• trade_flow_chord()

I will begin rewriting these using plotly