support Aria-label retro-fixing for Maths in XML

This is about MathJax elements and whether they are correctly displaying to screenreaders. It is going to need testing with a screenreader to distinguish whether this is incorrect use of MathJax, or site improve (which flagged this) doesn't understand MathJax.

the key question is whether role=presentation is correct here, as used to hide decorative elements from screenreaders. amd whether a screen-reader friendly alternative is being correctly specified.

example:
https://www.iastatedigitalpress.com/mmb/article/id/12562/

<span class="inline-formula mathml">
<span class="MathJax_Preview" style="color: inherit; display: none;"></span>
<span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML" tabindex="0" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>R</mi><mo stretchy="false">(</mo><mi>&#x3BB;</mi><mo stretchy="false">)</mo></mrow></math>" role="presentation" style="font-size: 103%; position: relative;">
<span id="MJXc-Node-1" class="mjx-math" aria-hidden="true">  </span>
<span class="MJX_Assistive_MathML" role="presentation">  </span>
</span>
<script type="math/mml" id="MathJax-Element-1">  </script>
</span>
</span>

Begin with the example URL and the supplied MathJax HTML; test it with a screenreader, focusing on role="presentation" and the assistive MathML alternative. Trace whether the markup is generated by Janeway or only reported by Siteimprove. Done means the problem ownership and required accessible markup are established, with the behavior verified against the example.