### What?
This PR contains a couple of fixes to the bulk upload process:
- Credentials not being passed when fetching, leading to auth issues
- Provide a fallback to crypto.randomUUID which is only available when
using HTTPS or localhost
### Why?
I use [separate admin and API URLs](#12682) and work off a remote dev
server using custom hostnames. These issues may not impact the happy
path of using localhost, but are dealbreakers in this environment.
### Fixes #
_These are issues I found myself, I fixed them rather than raising
issues for somebody else to pick up, but I can create issues to link to
if required._
a374aabd8d