Register if a clientcertificate (and if so, which one) is used for the request

[alextreme]

Currently the client-cert used (if one is used) isn't shown in django-lor. This would be useful as we had an issue where a client certificate was configured however this wasn't used in OF.

https://requests.readthedocs.io/en/latest/user/advanced/#client-side-certificates

Expected would be to see the path to the client certificate for a request if this is applicable, or otherwise the fact that a client certificate wasn't used for the request. Further details (for instance about the location of the key) aren't necessary imho.

[sergei-maertens]

-> check request.cert and request.verify for this