Action Network integration

[janbaykara]

[janbaykara]

CC @chrisdevereux

[janbaykara]

Wonder if we could piggyback off https://move-coop.github.io/parsons/html/stable/action_network.html or another API layer. From memory we've had trouble finding a decent Python binding for AN's API before though. E.g. isn't Parsons hard to install because of dependency pinning or something?

(We might want to add a note to the docs on "why another integrations library?" with some of this rationale.)