Fixes & improvements

• API: Added a pooler_enabled property to the project update API call to indicate whether or not connection pooling is enabled.
• API: Fixed several bugs that could cause intermittent 409 responses, which indicate a request conflict with the current state of the target resource.
• Control Plane: Implemented connection pooling support for Neon projects, allowing Neon to support a greater number of connections. For information about enabling connection pooling for a Neon project, see Connection pooling.