Use Guest collections to avoid extra authentication

[NelisDrost]

Flows currently pause after starting, requiring added authentication to resume.

See first link for why - basically the flow can't know what consents it needs until it interacts with a non-guest collection:
https://docs.globus.org/api/flows/working-with-consents/

How to create a guest collection with the SDK:
https://globus-sdk-python.readthedocs.io/en/stable/experimental/examples/endpoints_and_collections/create_guest_collection/index.html