Add delivery_email field to page_params.

This allows the frontend to use the `delivery_email`
field for display use.

zerver/lib/events.py

@@ -228,6 +228,7 @@ def fetch_initial_state_data(user_profile: UserProfile,
         state['user_id'] = user_profile.id
         state['enter_sends'] = user_profile.enter_sends
         state['email'] = user_profile.email
+        state['delivery_email'] = user_profile.delivery_email
         state['full_name'] = user_profile.full_name
 
     if want('realm_bot'):