Add more quick links to external resources

[nichtich]

Such as WebDewey Search and Norsk WebDewey:

<span>
    <a
      :href="`https://coli-conc.gbv.de/cocoda/app/?fromScheme=http%3A%2F%2Fdewey.info%2Fscheme%2Fedition%2Fe23%2F&from=${concept.uri}`"
      title="open in Cocoda"
      target="cocoda">&nesear;</a>
    <a
      :href="`https://deweysearchde.pansoft.de/webdeweysearch/executeSearch.html?query=${concept.notation[0]}`"
      title="open in WebDewey Search"
      target="webdewey_search">&#x1F50D;</a>
    <a
      :href="`https://data.ub.uio.no/skosmos/ddc/nb/page/?uri=${concept.uri}`"
      title="open in Norsk WebDewey"
      target="norsk_webdewey">no</a>
  </span>

This may also come with gbv/bartoc.org#76 so we can manage the links in BARTOC.

[nichtich]

Closing in favour of #60