Add interpolation option for `SimulationData.plot_field` method.

[FilipeFcp]

I would suggest implementing a variable for interpolation in the SimulationData.plot_field method, so the user has an easy way to plot a smooth field profile.

Without interpolation:

With interpolation:

In the graph above, the .interp method for the Xarray field data object was used to increase the density of points from the original grid points to 1000.

small priority

[tylerflex]

Hi @FilipeFcp could you implement this when you get time? should be pretty straightforward, like the last one. thanks!