Ian Botsford

Deprecating this PR in favor of using coroutine context.

Depends on [smithy-kotlin#745](https://github.com/awslabs/smithy-kotlin/issues/745).

In light of https://github.com/awslabs/aws-sdk-kotlin/issues/1396 we should re-examine this request and either provide clearer instructions for how to mock presigning operations and/or improve the mockability of presigning code.

@IgnatBeresnev is there an update on when the new UI designs will be released and the WCAG violations noted above will be fixed?