feature: navigate to nested-field

Allows navigation to nested-field="xyz", like in a <solid-link> element.

On a citizen project page:

<solid-link bind-resources nested-field="founder" next="myactor">Link to related Actor</solid-link>

Will also work within a requestNavigation event:

new CustomEvent("requestNavigation", {
  bubbles: true,
  detail: { "myactor", { "@id": "...", "nested-field": "founder" } },
})

Required for EP.