Add exclude_unreviewed param to GET /api/v2/search REST API (#11977)

Make it so normal search returns even unreviewed matches, but
autosuggestions do not.

Fix #11960

app/services/search_service.rb

@@ -60,7 +60,8 @@ class SearchService < BaseService
     TagSearchService.new.call(
       @query,
       limit: @limit,
-      offset: @offset
+      offset: @offset,
+      exclude_unreviewed: @options[:exclude_unreviewed]
     )
   end