\includegraphics: kpsewhich look up is not exhaustive

[xworld21]

Running a simple

\includegraphics{europasslogo.pdf}

will fail to find candidates, because the logic that tries with kpsewhich has a strange choice of hardcoded values https://github.com/brucemiller/LaTeXML/blob/70de862ff1997e228e8a0ee33ba61d1800adf189/lib/LaTeXML/Util/Image.pm#L52 Look up should use the same combination of extensions as for candidates in seach paths.