Fix #3696: API: handle boolean params consistently

* Use ApplicationRecord#attribute_matches to handle boolean attributes
  consistently in search methods.

* Add support for searching various boolean attributes that previously
  weren't supported.

app/models/wiki_page.rb

@@ -92,6 +92,9 @@ class WikiPage < ApplicationRecord
         q = q.where("other_names is null or other_names = ''")
       end
 
+      q = q.attribute_matches(:is_locked, params[:is_locked])
+      q = q.attribute_matches(:is_deleted, params[:is_deleted])
+
       params[:order] ||= params.delete(:sort)
       case params[:order]
       when "title"