Fix dimension ordering bug in UniversePlotCreator which led to wrong association of parameter dimensions

The bug was due to a different kind of ordering of parameter dimensions when they need to be assembled to form the universe coordinates for a plot. As the hierarchy is flat in the new _coords mapping added for that purpose, the ordering happens in a different fashion than in the original parameter space.

The bug was fixed by using the existing ordering of parameter dimensions that the original parameter space had already determined.

Thanks to @jeremiastraub for finding and reporting!

Can this MR be accepted?

• Bug fixed
• Test case added
• Changelog entry for v0.6.1 added
• Pipeline passing without warnings

Target branches:

• master
• Cherry-pick into release/0.6 as version 0.6.1