Add endpoint params to debug logs (#2936)

Debugging endpoint resolution can be difficult when the params being
used during resolution aren't logged. This PR adds that logging.

Example output below. It doesn't ordinarily have newlines and
indentation. I added those for clarity.
```
2023-08-22T00:27:54.363727Z DEBUG
invoke{service=s3 operation=ListObjectsV2}:try_op:try_attempt:
aws_smithy_runtime::client::orchestrator::endpoints: resolving endpoint
endpoint_params=EndpointResolverParams(TypeErasedBox[!Clone]:Params {
  bucket: Some("test-bucket"),
  region: Some("us-east-1"),
  use_fips: false,
  use_dual_stack: false,
  endpoint: None,
  force_path_style: false,
  accelerate: false,
  use_global_endpoint: false,
  use_object_lambda_endpoint: None,
  disable_access_points: None,
  disable_multi_region_access_points: false,
  use_arn_region: None
})
endpoint_prefix=None
```

----

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rust-runtime/aws-smithy-runtime/src/client/orchestrator/endpoints.rs

@@ -121,6 +121,7 @@ pub(super) async fn orchestrate_endpoint(
         .load::<EndpointResolverParams>()
         .expect("endpoint resolver params must be set");
     let endpoint_prefix = cfg.load::<EndpointPrefix>();
+    tracing::debug!(endpoint_params = ?params, endpoint_prefix = ?endpoint_prefix, "resolving endpoint");
     let request = ctx.request_mut().expect("set during serialization");
 
     let endpoint = runtime_components