resolves #17 publish the language support scripts and load into browser, if required (proposal 1)
- create helper function to vendor JS file in UI catalog
- vendor the scripts from lunr-languages if non-en languages are enabled
- set the SITE_SEARCH_LANGUAGES env var to a comma-separated list of non-en languages if non-empty
- move the responsibility of loading Lunr, the language support scripts, and the search index to the search script
- rename search-ui.js to search.js
- rename lunrSiteSearch.init to initSearch
- check for globalThis properly