Add unit-tests for GenerateS3URL and UploadFileToS3 steps.
Pull request: https://github.com/WebKit/WebKit/pull/12760
Committed 263023@main (aeba312790f6): <https://commits.webkit.org/263023@main> Reviewed commits have been landed. Closing PR #12760 and removing active labels.
<rdar://problem/108140369>