Improve types: Do not cast to "any"

[HarshaNalluru]

https://github.com/amqp/rhea-promise/blob/master/lib/session.ts#L68

Fixing this would require requesting rhea to provide more types to allow accessing fields such as "outgoing", "incoming" and "local" on the Session interface/type.

[HarshaNalluru]

Reference Azure/azure-sdk-for-js#14060 (comment)