Allow taxonomies to be used in routing.

Allows taxonomies to be used in routing.
 * Grouping: works
 * Categories: works, picks the first one
 * Tags: kinda works, picks the first one (not recommended)

Not sure if this syntax is ideal?

    chapterbinding:
      path: /{chapters}/{slug}
      defaults: { _controller: 'Bolt\Controllers\Frontend::record', 'contenttypeslug': 'kitchensinks', 'chapters': 'none' }
      requirements:
        chapters: [ 'Bolt\Controllers\Routing::getTaxonomyRequirement', ['chapters', 'none'] ]
      contenttype: kitchensinks

The `none` is only required in the case when an empty value is set for that `contenttype`. Usually you want anything in the URL to be non-empty.