FEATURE: Show votes in an "on voted" poll to the creator

This required properly plumbing the guardian into the serializer.

Notably, the default state in the client was not changed - if you haven't voted in
the poll, you need to click the button to view the results instead of the results
being immediately visible on page load.

Implements https://meta.discourse.org/t/-/138108

plugins/poll/lib/polls_updater.rb

@@ -93,7 +93,7 @@ module DiscoursePoll
 
         if has_changed
           polls = ::Poll.includes(poll_options: :poll_votes).where(post: post)
-          polls = ActiveModel::ArraySerializer.new(polls, each_serializer: PollSerializer, root: false).as_json
+          polls = ActiveModel::ArraySerializer.new(polls, each_serializer: PollSerializer, root: false, scope: Guardian.new(nil)).as_json
           post.publish_message!("/polls/#{post.topic_id}", post_id: post.id, polls: polls)
         end
       end