Allow setting of custom alternateName(s)

[sybrew]

Follow up from #663. See https://developers.google.com/search/docs/appearance/site-names#alternative.

Google proposed this Schema.org markup for alternameName:

<script type="application/ld+json">
  {
    "@context": "https://schema.org",
    "@type": "WebSite",
    "name": "Buttered Toast",
    "alternateName": ["BT", "B-T", "Buttered Toast Shop"],
    "url": "https://www.example.com/"
  }
</script>

For long names, such as "The SEO Framework," it would be nice to allow "TSF," but there's currently no proper way to add these alternate names.

When implemented, we should forgo automating this field like we currently do.