SDK does not deserialize s3control's signature error correctly

[jasdel]

Confirm by changing [ ] to [x] below to ensure that it's a bug:

• I've gone though the API reference
• I've checked AWS Forums and StackOverflow for answers
• I've searched for previous similar issues and didn't find any solution

Describe the bug
The SDK doesn't successfully parse error code and message from the signature error returned by S3 control. Example of error message in #863

Version of AWS SDK for Go?
v0.28.0

Version of Go (go version)?
v1.15.1

To Reproduce (observed behavior)
Make API call to s3control that results in invalid signature.

Expected behavior
Error to have code of SignatureDoesNotMatch and message of The request signature we calculated does not match the signature you provided. Check your key and signing method.

Got
2020/10/29 08:25:24 request failed, operation error S3 Control: ListJobs, https response error StatusCode: 403, RequestID: 81C695261D5B0C66, HostID: Jm3tTRaXSHjE7u4r5Thd8DTqm8Aq6wlqd44EhMgWKsMEaQE8zBp+1k9Mqv9daT/70mPhoCrMq2c=, api error UnknownError: UnknownError

See #863 for wirelog.

[github-actions]

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