Store remote votes URI (#10158)

* Store remote votes URI

* Add spec for accepting remote votes

* Make poll vote id generation work the same way as follows

app/lib/activitypub/activity/create.rb

@@ -241,7 +241,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
 
   def poll_vote?
     return false if replied_to_status.nil? || replied_to_status.poll.nil? || !replied_to_status.local? || !replied_to_status.poll.options.include?(@object['name'])
-    replied_to_status.poll.votes.create!(account: @account, choice: replied_to_status.poll.options.index(@object['name']))
+    replied_to_status.poll.votes.create!(account: @account, choice: replied_to_status.poll.options.index(@object['name']), uri: @object['id'])
   end
 
   def resolve_thread(status)

app/models/poll_vote.rb

@@ -9,6 +9,7 @@
 #  choice     :integer          default(0), not null
 #  created_at :datetime         not null
 #  updated_at :datetime         not null
+#  uri        :string
 #
 
 class PollVote < ApplicationRecord
@@ -20,6 +21,8 @@ class PollVote < ApplicationRecord
 
   after_create_commit :increment_counter_cache
 
+  delegate :local?, to: :account
+
   private
 
   def increment_counter_cache

app/serializers/activitypub/vote_serializer.rb

@@ -6,7 +6,7 @@ class ActivityPub::VoteSerializer < ActiveModel::Serializer
                :in_reply_to, :to
 
     def id
-      [ActivityPub::TagManager.instance.uri_for(object.account), '#votes/', object.id].join
+      ActivityPub::TagManager.instance.uri_for(object) || [ActivityPub::TagManager.instance.uri_for(object.account), '#votes/', object.id].join
     end
 
     def type