primaryClass alias for arXiv entries

[matchatealeaf]

According to the biblatex documentation, archivePrefix and primaryClass were added as aliases for eprinttype and eprintclass respectively for arXiv compatibility. See: https://mirrors.ctan.org/macros/latex/contrib/biblatex/doc/biblatex.pdf#subsubsection.2.2.5

However, it seems that only archivePrefix was implemented in this crate for eprinttype, and primaryClass for eprintclass is missing.

https://github.com/typst/biblatex/blob/190576a2de80f156f7c30ec105735820a5a168e4/src/lib.rs#L764-L775

https://github.com/typst/biblatex/blob/190576a2de80f156f7c30ec105735820a5a168e4/src/lib.rs#L830

Is there a reason for the exclusion of primaryClass for eprintclass, or is it simply missed?