FEATURE: Use Postgres unaccent to ignore accents (#16100)

The search_ignore_accents site setting can be used to make the search
indexer remove the accents before indexing the content. The unaccent
function from PostgreSQL is better than Ruby's unicode_normalize(:nfkd).

lib/search/grouped_search_results.rb

@@ -120,7 +120,7 @@ class Search
       blurb = nil
 
       if scrub
-        cooked = SearchIndexer.scrub_html_for_search(cooked)
+        cooked = SearchIndexer::HtmlScrubber.scrub(cooked)
 
         urls = Set.new
         cooked.scan(Discourse::Utils::URI_REGEXP) { urls << $& }