Add support for front matter options via `extras` field in reference managers

[Geo]

Goals

Add support for front matter options (e.g. projects, categories) via reference manager's extras field.

This could simplify the process of importing publications, effectively using the reference manager as the CMS for publications.

Details

Configuration of front matter options via the reference manager's extras field will streamline the import process and alleviate the need to edit any of the automatically generated Markdown files. Hence, all publication editing can be performed in the user's existing reference management tool.

For example, this would enable users to set front matter options such as categories within their reference manager.

There are many limitations to the extras field in reference managers. We'd need to design a data structure and consider how multiple front matter options, including lists and nested key-value pairs, are stored in a flat extras field.

[Gregor von Laszewski]

I do find the support of bibtex important. Please do not drop it.

A workaround for the issue of tags not being set has been posted in https://github.com/laszewski/laszewski.github.io/blob/master/bin/featured.py
The use is documented in a Makefile such as in https://github.com/laszewski/laszewski.github.io/blob/master/Makefile

The makefile contains the following tags:

make bib
which cleans the bib file and removes the mont tags with strings

make mark_class_books
which marks some of the bibtex related documents for hugo with the tag that in that case is used for a filter.

it would be much nicer if we would have an academic import that has tags included.

However, maybe I do not use the import correctly?