Use Temporal for orchestration

[hellais]

This implements one of the options outlined inside of: https://github.com/ooni/data/issues/46

What I like about it:

• It doesn't require a lot of boilerplate and results in a more compact system
• It's a well thought out system with strict guarantees
• The people behind it created uber/cadence
• It has an SDK for go and javascript too
• It's quite minimal and unopinionated
• The web UI looks slick and is nice to work with
• The documentation looks good
• It has a cloud option

What I don't like:

• The execution model of ensuring workflows are deterministic is sane, but a bit tricky to work with (to get it up and running quickly I kind of cheated and just marked a lot of things as unsafe)
• Since it's unopinionated it doesn't have as much stuff around the orchestration part or tells you how to do things
• It's a bit less of a "batteries included" solution compared to other solutions
• The fact it supports many languages makes me worry if they have the capacity to support all these SDKs. I assume python should be first class support, but I'm not sure of that.
• The billing of the cloud option is quite confusing

[hellais]

This has been merged as part of #60