Is your suggestion for improvement related to a problem? Please describe.

I want to be able to create automatic groups by year when I have the date field set.
Currently, JabRef creates a group for every YYYY-MM-DD entry.

Describe the solution you'd like
An option to create an automatic group by year. It should work independent of bibtex and biblatex fields (e.g. if year field or date field is set).

Additional context
Requested in the forum https://discourse.jabref.org/t/separator-with-specified-keywords-selection-for-groups/4042