add submission id var

lib/submitters/submit_values.rb

@@ -131,6 +131,8 @@ module Submitters
 
       value.to_s.gsub(VARIABLE_REGEXP) do |e|
         case key = ::Regexp.last_match(1)
+        when 'id'
+          attrs['submission_id']
         when 'time'
           if with_time
             I18n.l(Time.current.in_time_zone(template.account.timezone), format: :long, locale: template.account.locale)