How can I add a new table to the existing database in Medplum, and how can I use that custom table with the Medplum SDK? I’ve looked into the extension feature, which allows adding new attributes to existing tables. However, we want to create a completely new table and use it with or without the Medplum Client SDK. Is this possible? Another thing if you would love to tell me about estimated pricing with self hosting at enterprise level then if it be highly appreciated