Provide a mechanism to abort an upload.
When calling fs#upload_from_stream, the upload will be aborted if the source stream raises an error.
When an upload is aborted any chunks already uploaded will be deleted.
Abort raises an error if it is unable to successfully abort the upload (for example, if an error occurs while deleting any chunks already uploaded). However, if the upload is being aborted because the source stream provided to upload_from_stream raised an error then the original error should be re-raised.
Abort also closes the Stream, or at least places it in an aborted state, so any further attempts to write additional content to the Stream after Abort has been called fail immediately.