feat(html): enhance html entrants with id and anchors

[lewisacidic]

We should add linking support in HTML. This would be a hacky and finicky change, and maybe should be in citeproc-js, but .

We want to support this (fun example from the citeproc-js docs):

<h1> The Discovery of Wetness </h1>
<p>
  While it has long been known that rocks are dry<sup>[<a href="#ref-a">1</a>]</sup> and that air is moist<sup>[<a href="#ref-b">2</a>]</sup> it has been suggested by Source [<a href="ref-c">3</a>]  that water is wet.
</p>
<div class="csl-bib">
  <h2 class="csl-bib-title">References</h2>
  <div class="csl-bib-body">
    <div id="ref-a" class="csl-entry">[1] John Noakes, The Dryness of Rocks (1952).</div>
    <div id="ref-b" class="csl-entry">[2] Richard Snoakes, The Moistness of Air (1967).</div>
    <div id="ref-c" class="csl-entry">[3] Jane Roe, The Wetness of Water (2000).</div>
  </div>
</div>

which looks like:

The Discovery of Wetness

While it has long been known that rocks are dry^[1] and that air is moist^[2] it has been suggested by Source [3] that water is wet.

References

[1] John Noakes, The Dryness of Rocks (1952).

[2] Richard Snoakes, The Moistness of Air (1967).

[3] Jane Roe, The Wetness of Water (2000).

---

Tasks

• Splicing the anchors into the citation.
  • Can use citation.sortedItems to get the order, although collapse-able might make this hard
  • just link the first reference if collapsed
• Splicing the id's into the bibliography
  • should be simple to put after the div, all of them start div class="csl-entry"
• citeInText (hardest, will need even more hacks there...)