Add publications to other resource types

[glpoulter]

Solvers, test cases and projects should have on their pages any relevant publications.

Present this like rsd did with mentions originally? eg with a section on the page like this:

[glpoulter]

Or add related publications in a more subtle way eg with simply Ransley et al (2021) (for example) in the Related row for projects, and the metadata bar for test cases etc. (The ref would link to the paper)