Fixed colorscale 0-point in visualization of Wigner functions

[JacobHast]

Before posting a feature request

• [X] I have searched exisisting GitHub issues to make sure the feature request does not already exist.

Feature details

I would like the offset of the colorscale of Wignerfunction plots to be consistent such that the color indicating W = 0 is the same for different states, and not scaled according to the min and max of W of the particular state I'm plotting

As a bonus-feature, it might be nice to also show a small color bar for these plots

Implementation

No response

How important would you say this feature is?

1: Not important. Would be nice to have.

Additional information

No response