Switch api.ooni.io to be served from AWS

[hellais]

This is about starting to use the AWS frontend as the real frontend for probes/explorer/etc.

Once we feel confident that all the services which we have rewritten are working as intended with the rest and that the setup on AWS is not going to lead to any downtime, we should make the switch.

We should do in two stages:

• Have a main entry point which is api.ooni.org and configure Explorer and Probes to speak to it and validate that everything is working as intended
• Change DNS to have api.ooni.io point to AWS and have the load balancer rules just transparently proxy everything
• Make sure there is no more traffic hitting backend-fsn, if so port missing services over (see: Port backend/legacyapi components over to the ooniapi services pattern backend#807)
• Incrementally change the rules to enable one service at a time

[hellais]

We should make sure that https://api.prod.ooni.io/ still works, since DW is using this in their app.

[jbonisteel]

Can be a new dev, to be reassigned in Jan

[hellais]

We ran some numbers with @DecFox and concluded that in order to not get killed by bandwidth costs, we will have to do this after we have done #122 .

Adding that as a child issue to this one.