Add Tor Support for Bitcoin Core Nodes Connecting to Civkit

[MarketMadi]

As an orderbook runner, I need to be able to connect to both clearnet and tor for bitcoin nodes. Tor has not yet been implemented.

A new listener will need to be implemented to allow tor connections. A good starting point is server.rs and bitcoind_client.rs to review and add tor support.

Here are some more contextual and supporting documents
https://github.com/bitcoin/bitcoin/blob/master/doc/tor.md
https://github.com/bitcoin/bitcoin/blob/master/src/torcontrol.cpp

[IAmBabaorum]

I think there are 2 different things that can be achieved:

• a) implementing tor support such as a civkit sample (the client) can connect to civkit node (the server)
• b) connecting to a non-hosted bitcoin node over tor from the civkit node

I believe for now it might be easier to assume server operator run their own bitcoin nodes locally.

About a), I think it’s about adding a new thread torcontrol.rs implementing the Tor Control protocol (https://spec.torproject.org/control-spec/protocol-outline.html) to port bind with tor as a proxy. A new TorControlThread can be started in server main initialization sequence.