Bibliography changes on authors, editors, publishers, dates

[Omikhleia]

Closes #2052

Features

• Some files split and reorganized (minimal refactor for now)
• Support more Bib(La)TeX name fields (author but also editor, shortauthor, shorteditor, translator, holder) and parse/split names earlier (at entry parsing rather than on each use)
• Partial support for BibLaTeX extended date field (ISO ETDF)
• Month regularization (support 3-letter short code as BibTeX, but also 1-12 numbers)

Known issue

• (See also in-code comment in the Chicago-style implementation file.) Date formatting obeys English only (as "Month Day, Year" with the month in English). This is still better that the previous behavior (raw as-is value of the BibTeX field), but obviously not general.

With the ongoing effort on CSL support, the above know issue might be acceptable for now and not worth addressing. The underlying question, however, is whether we want to consider still supporting the "legacy" style logic; and if so, how much efforts we are ready to involve in it...

[alerque]

Rebased commits have only been modified by filtering the Lua through stylua to normalize formatting, no other changes. (For branches like this this has to be done starting at the last commit and working backwards to the first so the style changes get set where they were made without introducing conflicts with later commits that haven't been restyled yet.)