Migrate keywords from npm package to jsDelivr

[hmaier-fws]

Keywords are currently obtained from the NPM mdkeywords package. Changing keywords requires rebuilding and publishing the keyword package. Switching to a content delivery system such as jsDelivr will allow access to updated keywords without the need for a separate process to rebuild and publish a NPM module.

This will also position the mdEditor to more easily support custom keywords from other harvest sources.

See also:

• #Add support for creating reusable Thesaurus mdEditor#113
• #Custom Vocabularies from External Thesauri mdEditor#450,
• #Allow profile to specify vocabularies to be included in metadata records mdEditor#459