Allow toggling fail-fast behavior of workflows via an input #15
Description
The only possible note is that we may want to have the fail-fast behaviour be turned on/off with a workflow input. This would allow us to fail fast in the merge queue but we may want to allow all tasks to complete on PRs to give info when tests would only fail on certain OSes, this is a kinda niche scenario though.
Originally posted by @TomAFrench in #9 (review)