Preserve fancyhdr.sty content

[dginev]

We have a stub in place for fancyhdr.sty, which is expedient in discarding the header content. We've had an arXiv author request more complete support, as they had valuable licensing information in the header.

An example article is 2306.06056.

As an example of the stub binding lines: https://github.com/brucemiller/LaTeXML/blob/dfc3bc96306b7f14ace5b4241a9f477a6f433955/lib/LaTeXML/Package/fancyhdr.sty.ltxml#L27-L29

Minimal motivating snippet:

\documentclass{article}
\usepackage{fancyhdr}
\begin{document}
\thispagestyle{fancy}
\fancyfoot[L]{\copyright 2024 IEEE.  Personal use of this material is permitted.  Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.}
\section{Introduction}

\newpage
\section{And so on...}
\end{document}