Implement commercial calendars: booking_open, specialists, expire without type downgrade.

Refs EventHub/EventHubBack#54

src/infra/infra_sup.erl

@@ -50,6 +50,12 @@ init([]) ->
       restart => permanent,
       shutdown => 5000,
       type => worker,
-      modules => [migration_engine]}
+      modules => [migration_engine]},
+    #{id => subscription_worker,
+      start => {subscription_worker, start_link, []},
+      restart => permanent,
+      shutdown => 5000,
+      type => worker,
+      modules => [subscription_worker]}
   ],
   {ok, {SupFlags, Children}}.