ENH: Allow context-based back navigation

[jsheunis]

Relevant issue: sfb1451/metadata-catalog#34

Another idea: The catalog URL could support a dedicated context identifier. IOW we make the "back target" explicit. If the URL contain this information, some kind of "back link" is shown, if not, then not.
This would allow users to provide contextualized catalog links, ie. point to a specific dataset version, in the context of another (super)dataset.

[jsheunis]

One drawback of this would be that a "dataset in the context of a superdataset" implies a direct parent-child relationship, i.e. not multiple levels of nesting. This would restrict the possibility to a single back operation, and might confuse the user if they would expect another back button to be possible. Not necessarily a reason one should do it, just noting the possibility of unexpected UX.