[pg] Updated Client and Pool config types according to docs (#40728)
[pg] Updated Client and Pool config types according to docs (#40728)

* Fixed Client and Pool config types for pg

* Add ConnectionConfig alias

markogresak/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped