Implement API gateway for api.ooni.io

[hellais]

Basically we should setup in terraform an API gateway that allows us to route traffic to the new oonidatapi, but keep most of it pointing still to the old legacy instance on backend-fsn.

This would allow us to centrally manage the paths and handle failing over to the old one if something breaks badly.

I will drop in here some links to stuff to look at:

• https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/apigatewayv2_route
• https://docs.aws.amazon.com/apigateway/