Teach tctl how to interact with other environments

[HalosGhost]

Many have expressed interest in being able to run experiments on other cloud environments besides AWS (e.g., Azure, GCP, etc.). I am unsure if there is a shared SDK abstraction layer which would allow us to swap out AWS-specific features for portable options, but if such a library exists, this lift would involve implementing that library. If not, the lift is far more significant: more or less, creating a small layer of our own, and plugging the platform-specific pieces into the abstraction.

This isn't going to be done in the short-term (at least not, by upstream), the benefits would be massive, but we already have an AWS environment setup, the benefit of porting to other environments doesn't directly help our research right now. However, we are definitely interested in this future, and would gladly accept PRs!