`plot_residuals` as panel

[Francesco Bruzzesi]

Description

In current implementation of plot_residuals, all residuals are stacked into the same plot.
The option to have one plot per entity, similarly to how plot_panel behaves, would be a nice to have.

Expected Result (*)

An image is worth a 16x16 words:

(*) Generated on random data

(Possible) implementation

The "out of the box" solution could be to add a parameter to require such behavior (e.g. as_panel: bool or kind: Enum('Kind', ['STACKED', 'PANEL']) and then to specify facet_row="entity" option in px.histogram

Edit: I am happy to take this task if we agree on how the result should look like 😊