BibTeX: Add editor to 5 types

[carlinmack]

A user on Zenodo support has identified that we do not correctly add the editor field to the BibTeX output.

According to the original manual (1988 by BibTeX co-author Oren Patashnik), the editor field should be added where available in:

• book
• inbook
• incollection
• inproceedings
• proceedings

Example record where the editors would be expected to appear in the BibTex: https://zenodo.org/records/13912515

CC @tmorrell

[carlinmack]

CC @TomazErjavec see the above :)

[TomazErjavec]

Thanks @carlinmack for notifying me - you summarised it well, nothing to add, except wishing that you manage to add "editor" to BibTeX export!