Adds S3CrossRegion clients and codegen for retrieving bucket name#4008

cenedhryn merged 3 commits intocross_region_bucket_access/project_branchaws/aws-sdk-java-v2:cross_region_bucket_access/project_branchfrom

salande/crossregion-client-bucket-paramsaws/aws-sdk-java-v2:salande/crossregion-client-bucket-paramsCopy head branch name to clipboard