Restores using ubuntu-latest.
Basically, at some point in the last year the existing Docker e2e tests started
failing. I'm unclear if this is an issue with the OS, the docker packages, or
what. This just tries to find a solution.
* Rename the coins folder to networks
Ethereum isn't a coin. It's a network.
Resolves#357.
* More renames of coins -> networks in orchestration
* Correct paths in tests/
* cargo fmt