Part of https://github.com/serai-dex/serai/issues/682.
We don't remove the use of `tokio::sync::Mutex` now as `hyper` pulls in
`tokio::sync` anyways, so there's no point in replacing it. This doesn't yet
solve TLS for non-`tokio` `Client`s.
* 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