Add onceoff job for uploads migration of column extension. Simplify filetype search and related rspec tests.

lib/search.rb

@@ -457,16 +457,16 @@ class Search
   end
 
   advanced_filter(/filetypes?:([a-zA-Z0-9,\-_]+)/) do |posts, match|
-    file_extensions = match.split(",")
+    file_extensions = match.split(",").map(&:downcase)
 
     posts.where("posts.id IN (
       SELECT post_id FROM topic_links
-      WHERE extension IN (?)
+      WHERE extension IN (:file_extensions)
       UNION
       SELECT post_uploads.post_id FROM uploads
       JOIN post_uploads ON post_uploads.upload_id = uploads.id
-      WHERE lower(uploads.extension) IN (?)
-      )", file_extensions, file_extensions)
+      WHERE lower(uploads.extension) IN (:file_extensions)
+      )", {file_extensions: file_extensions})
   end
 
   private