Add REST API for Web Push Notifications subscriptions (#7445)

- POST /api/v1/push/subscription
- PUT /api/v1/push/subscription
- DELETE /api/v1/push/subscription
- New OAuth scope: "push" (required for the above methods)

app/serializers/initial_state_serializer.rb

@@ -2,7 +2,9 @@
 
 class InitialStateSerializer < ActiveModel::Serializer
   attributes :meta, :compose, :accounts,
-             :media_attachments, :settings, :push_subscription
+             :media_attachments, :settings
+
+  has_one :push_subscription, serializer: REST::WebPushSubscriptionSerializer
 
   def meta
     store = {

app/serializers/rest/web_push_subscription_serializer.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class REST::WebPushSubscriptionSerializer < ActiveModel::Serializer
+  attributes :id, :endpoint, :alerts, :server_key
+
+  def alerts
+    object.data&.dig('alerts') || {}
+  end
+
+  def server_key
+    Rails.configuration.x.vapid_public_key
+  end
+end

app/serializers/web/notification_serializer.rb

@@ -54,7 +54,7 @@ class Web::NotificationSerializer < ActiveModel::Serializer
 
     def access_token
       return if actions.empty?
-      current_push_subscription.access_token
+      current_push_subscription.associated_access_token
     end
 
     def message