The function first checks if the full reference distributions of
[compare_gvar()] are saved using the argument 'return_all' set to TRUE. If
not, an error is thrown.
Using the "name_a" and "name_b" arguments allows for custom labeling of the
two models in the plot.
The function generates two density plots using `ggplot2`, one for the
temporal network (beta) and another for the contemporaneous network (pcor).
The density distributions are filled with different colors based on the
corresponding models (mod_a and mod_b). The empirical distances between the
networks are indicated by red vertical lines.