Support pushing and receiving updates to poll tallies (#10209)

* Process incoming poll tallies update

* Send Update on poll vote

* Do not send Updates for a poll more often than once every 3 minutes

* Include voters in people to notify of results update

* Schedule closing poll worker on poll creation

* Add new notification type for ending polls

* Add front-end support for ended poll notifications

* Fix UpdatePollSerializer

* Fix Updates not being triggered by local votes

* Fix tests failure

* Fix web push notifications for closing polls

* Minor cleanup

* Notify voters of both remote and local polls when those close

* Fix delivery of poll updates to mentioned accounts and voters

app/serializers/activitypub/update_poll_serializer.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class ActivityPub::UpdatePollSerializer < ActiveModel::Serializer
+  attributes :id, :type, :actor, :to
+
+  has_one :object, serializer: ActivityPub::NoteSerializer
+
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object), '#updates/', object.poll.updated_at.to_i].join
+  end
+
+  def type
+    'Update'
+  end
+
+  def actor
+    ActivityPub::TagManager.instance.uri_for(object)
+  end
+
+  def to
+    ActivityPub::TagManager.instance.to(object)
+  end
+
+  def cc
+    ActivityPub::TagManager.instance.cc(object)
+  end
+end