Generate Session ID on server for synchronized editor

This change allows us to use the session ID immediately for the connection_change and connection_status methods. Hence, we can identify different browser sessions of the same user.

db/migrate/20230912162208_require_session_id_for_event_synchronized_editor.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class RequireSessionIdForEventSynchronizedEditor < ActiveRecord::Migration[7.0]
+  def change
+    change_column_null :events_synchronized_editor, :session_id, false
+  end
+end