how to copy files to GCS with signedurl

is it possible to use signedURL to copy files to GCS. ``` gsutil cp -r gs://bucket/ ``` without having to use a service account (*.json file) ? I have a use case where public user need to be temporary given a short-live token to upload files to GCS, but I do not want them to enforce them to have Google account.

No source file or test is named. Start at the gsutil cp signed-URL flow described in the issue and verify whether GCS supports the requested temporary unauthenticated upload path; done means documenting a supported command or a clear limitation and alternative.

Written by the indexing model from the issue text.