Look into https + aws4

[sam-goodwin]

Thanks to @krivachy for the suggestion of https://www.npmjs.com/package/aws4. Also found https://github.com/mhart/aws4fetch which works with Fetch API. I wonder if we can/should support both?

Bundle impact:

• aws4 (8kB min, 2.9kB min + gzip) - https://bundlephobia.com/package/aws4@1.12.0
• aws4fetch (7.2kB min, 2.9kB min + gzip) - https://bundlephobia.com/package/aws4fetch@1.0.17

I think this approach would work better for browser environments but maybe worse for Lambda since the @aws-sdk/* libraries are included in the Lambda bundle. Still worth testing though, especially since importing @AWS-SDK has proven to be slow.