Provide a way for customers to configure the underlying Secrets Manager Client.

[simonmarty]

Currently, we do not provide customers a way to configure the Secrets Manager Client used to retrieve secrets through the SSCD provider.
Customers have requested the ability to configure endpoints, retry strategy, etc. Similar to how they can for the Secrets Manager Caching libraries.

Child Issues

#141

[jbct]

We should make the Go client QPS and Burst configurable and have an internal backlog item to address.