Add a way to render a separate link column

[bprusinowski]

Nice, @bprusinowski 🎉 Maybe the field labelling is still a bit jargony for non-technical users. Could we consider something along the lines of "Link column" for Target dimension, "Link argument" for Source dimension? Also, I still like the links at the end of the rows (the initial behaviour) and think this could still be valuable for some users. We might want to consider keeping this functionality as an additional option in the dropdown. What do you think?

cc @sosiology

Originally posted by @adintegra in https://github.com/visualize-admin/visualization-tool/issues/2486#issuecomment-3515595093