Extract feed routes (#2269)

* Extract feed routes from invidious.cr
* Removes the deprecated route for /feed/top
* Deprecate /view_all_playlist & use /feed/playlists
* Move feed views into their own directory

* Add haltf method to halt current route context
* Change status_code + return blocks to use haltf

* Set appropriate response headers for RSS routes

src/invidious/routes/misc.cr

@@ -17,7 +17,7 @@ module Invidious::Routes::Misc
       end
     when "Playlists"
       if user
-        env.redirect "/view_all_playlists"
+        env.redirect "/feed/playlists"
       else
         env.redirect "/feed/popular"
       end