quicksearch in browser autocomplete #1079
Description
Suggestion from @pepelsbey:
I wonder if we could also support suggestions endpoint [in the Firefox add search engine UI] (Suggestions URL under Advanced option). For example, Ecosia’s URL is https://ac.ecosia.org/autocomplete?q=%s&type=list
This should be relatively trivial to do in our cloud function, repurposing the quicksearch logic from fred. Return format is described here: https://github.com/dewitt/opensearch/blob/master/mediawiki/Specifications/OpenSearch/Extensions/Suggestions/1.1/Draft%201.wiki#user-content-JSONformatted_search_suggestion_responses
We should also add the suggestions endpoint to our opensearch.xml, described here: https://github.com/dewitt/opensearch/blob/master/opensearch-1-1-draft-6.md#the-url-element
While we're at it, we should check if there's anything else to add to our opensearch.xml: at least a self-reference for auto-updating looks like it would be useful.