PostgreSQL Support for BuildBuddy

PostgreSQL Support for BuildBuddy has been introduced, allowing users to replace MySQL or SQLite with a PostgreSQL database backend by specifying an endpoint. To set up the new backend, users need to install PostgreSQL and create a user and database. The PostgreSQL connection can be specified via command line flags or in the BuildBuddy YAML config. Switching to this new backend results in a fresh BuildBuddy instance, requiring users to create new users and update API keys if using authentication. Feedback and suggestions for future improvements are welcome at [email protected] or on Slack.