[C++] Investigate new S3 CRT client in AWS SDK

[asfimport]

See the explanations given upstream in https://github.com/aws/aws-sdk-cpp/wiki/Improving-S3-Throughput-with-AWS-SDK-for-CPP-v1.9#working-with-the-new-s3-crt-client

The S3 CRT client might improve performance on transfers, and might also simplify dependencies (since AFAIU it doesn't use libcurl). Though that remains to be validated.

Reporter: Antoine Pitrou / @pitrou

_{Note: This issue was originally created as ARROW-14561. Please see the migration documentation for further details.}