Investigate plotting functionality

[priscavdsluis]

What is the need for this task.
There are several plotting functions to plot the network, but they currently do not work. It might be handy to have these functions anyway.

What is the task?
We should take a look at test_net.plot_network and the plot function written in the tutorial plotting_a_network.md
Maybe it is nice to add plotting utilities to a dedicated class that users can also use?

Additional context
Version: Hydrolib-core 0.3.1

[veenstrajelmer]

Alternatively, xugrid (or dfm_tools) can be used: #241 (comment)