Bug 22445: Custom cover images - opac reviews

Bug 22445: Custom cover images - opac reviews

Test plan:
- enable OpacShowRecentComments
- make a comment (OPAC)
- approve it (staff)
- click 'Recent comments' (OPAC)
=> You should see the custom cover

Sponsored-by: Orex Digital
Signed-off-by: Hayley Mapley <hayleymapley@catalyst.net.nz>
Signed-off-by: Hugo Agud <hagud@orex.es>
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Michal Denar <black23@gmail.com>
Signed-off-by: Kyle Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>