show instance specific feature data

[svigerske]

Transfer of issue https://git.zib.de/optimization/rubberband-config/-/issues/47, created by @jakobwitzig:

It would be very nice if some features, e.g., number of (binary / integer / cont) variables or number nonzero objective coefficients, are added to the "long table". This might be related to https://git.zib.de/optimization/rubberband-config/-/issues/46, because those columns could be hidden by default and activated by the user.