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/workers/activitypub/distribute_poll_update_worker.rb

@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+class ActivityPub::DistributePollUpdateWorker
+  include Sidekiq::Worker
+
+  sidekiq_options queue: 'push', unique: :until_executed, retry: 0
+
+  def perform(status_id)
+    @status  = Status.find(status_id)
+    @account = @status.account
+
+    return unless @status.poll
+
+    ActivityPub::DeliveryWorker.push_bulk(inboxes) do |inbox_url|
+      [payload, @account.id, inbox_url]
+    end
+
+    relay! if relayable?
+  rescue ActiveRecord::RecordNotFound
+    true
+  end
+
+  private
+
+  def relayable?
+    @status.public_visibility?
+  end
+
+  def inboxes
+    return @inboxes if defined?(@inboxes)
+    target_accounts = @status.mentions.map(&:account).reject(&:local?)
+    target_accounts += @status.reblogs.map(&:account).reject(&:local?)
+    target_accounts += @status.poll.votes.map(&:account).reject(&:local?)
+    target_accounts.uniq!(&:id)
+    @inboxes = target_accounts.select(&:activitypub?).pluck(&:inbox_url)
+    @inboxes += @account.followers.inboxes unless @status.direct_visibility?
+    @inboxes.uniq!
+    @inboxes
+  end
+
+  def signed_payload
+    Oj.dump(ActivityPub::LinkedDataSignature.new(unsigned_payload).sign!(@account))
+  end
+
+  def unsigned_payload
+    ActiveModelSerializers::SerializableResource.new(
+      @status,
+      serializer: ActivityPub::UpdatePollSerializer,
+      adapter: ActivityPub::Adapter
+    ).as_json
+  end
+
+  def payload
+    @payload ||= @status.distributable? ? signed_payload : Oj.dump(unsigned_payload)
+  end
+
+  def relay!
+    ActivityPub::DeliveryWorker.push_bulk(Relay.enabled.pluck(:inbox_url)) do |inbox_url|
+      [payload, @account.id, inbox_url]
+    end
+  end
+end