Add speculative prerendering for arbitrary URL patterns

[rviscomi]

The current implementation of the Speculation Rules API uses the older input list of URLs. Since then, the API has added the ability to speculatively prerender or prefetch patterns of URLs at a specified eagerness level, for example:

<script type="speculationrules">
{
  "prerender": [{
    "where": {
      "href_matches": "/*"
    },
    "eagerness": "moderate"
  }]
}
</script>

This is a FR to update the quicklink implementation to utilize the eagerness setting, which should add more flexibility to the way sites can prerender content. Inputs could be an allowlist or blocklist of URL patterns and the eagerness. The default eagerness is conservative but similar to the Speculative Loading WordPress plugin, quicklink could default to moderate eagerness.

cc @tunetheweb @gilbertococchi