Show version information more prominently

Created by: Zaharid

We have #748 and #786 to know which versions of the code the fits were ran with. It would be nice to have that in vp and in particular somewhere in the vp report.

I think the idea would be to have an action that takes a fit and returns a text with the version script in the happy case where all are the same and shouts at you when they are different. That is easily achieved by reading all json files into a set.

def fit_code_version(fit) -> str

Should probably return something like "undefined" for older fits.