Show name even if FN vCard field is missing

Is your feature request related to a problem? Please describe.

After exporting my contacts from some other service (I think Outlook or Thunderbird), for half of my contacts the vCard FN field (which is mandatory according to the RFC https://datatracker.ietf.org/doc/html/rfc6350#section-6.2.1) was missing while importing (not Nextclouds fault). I never noticed that issue in other programs, since they substituded a missing FN vCard fields with the N field. In Nextcloud's case they get shown as the space character.

Describe the solution you'd like

Show a concatenation of the N field as contact name, even if FN is missing.

Describe alternatives you've considered

Automatically create a FN field out of N fields, this could however introduce unwanted display of names.

Additional context

After the import my contact list looks like this:

(Yes those are all contacts and they show the first/last name fields upon opening)

I could probably try to implement this if this is a feature that would be requested.

No files, tests, or entry points are named. Start by tracing the contact list rendering and vCard import handling, then reproduce the case where FN is absent but N is present. Done means such contacts display a concatenated N value instead of a blank or space character, without requiring creation of a new FN field.