Add notifications of severed relationships (#27511)

app/models/account_relationship_severance_event.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+#
+# == Schema Information
+#
+# Table name: account_relationship_severance_events
+#
+#  id                              :bigint(8)        not null, primary key
+#  account_id                      :bigint(8)        not null
+#  relationship_severance_event_id :bigint(8)        not null
+#  created_at                      :datetime         not null
+#  updated_at                      :datetime         not null
+#
+class AccountRelationshipSeveranceEvent < ApplicationRecord
+  belongs_to :account
+  belongs_to :relationship_severance_event
+
+  delegate :severed_relationships, :type, :target_name, :purged, to: :relationship_severance_event, prefix: false
+
+  before_create :set_relationships_count!
+
+  private
+
+  def set_relationships_count!
+    self.relationships_count = severed_relationships.where(local_account: account).count
+  end
+end