Add more search providers

[janheinrichmerker]

Here are additional lists to consider:

• https://seirdy.one/posts/2021/03/10/search-engines-with-own-indexes/
• https://www.searchenginemap.com/
• https://searchengine.party/ (includes templates for URL query parsers)
• https://thenewleafjournal.com/a-2021-list-of-alternative-search-engines-and-search-resources/ (includes some templates for URL query parsers)
• https://github.com/matomo-org/searchengine-and-social-list/blob/master/SearchEngines.yml (Matomo's list of search engines)