Non-refundable streams in Flow v1.1.0

[smol-ninja]

RustyRabbit (from Cantina) suggested to add a feature to be able to set stream "non-refundable".

Some use cases

• Create a non-refundable stream so that other people can participate in funding without having to trust the sender
• Gitcoin grants. Imagine Gitcoin using Flow to create streams towards grantee which can be funded by anyone.

Starting this discussion to track similar feature requests from Flow users.