Feature Request

Is your feature request related to a problem? Please describe

When the connection is closed unexpectedly it throws a PostgresConnectionClosedException. I would like to handle this scenario programmatically, however, it currently isn't possible to catch PostgresConnectionClosedException because it's package-private.

For example, if I'm listening to notifications and want to restart the connection or channel.

Describe the solution you'd like

I would like for PostgresConnectionClosedException to be public so it can be explicitly caught.

Describe alternatives you've considered

Presently the only alternative I'm aware of is catching R2dbcNonTransientResourceException and checking for the "UNEXPECTED" error message. This isn't ideal because it's not as clear as catching the specific exception, and the message could change in the future.