Add bitcoin and monero onion examples

[sneurlax]

• Add Bitcoin onion example.
• Sync lib/socks_socket.dart with cypherstack/tor.
• Pin socks5_proxy to working version in example.

@icota, I also have a Monero onion example ready. It's similar so I wondered if it should be included. Let me know if you want that in, as well

[sneurlax]

Looks like

with this output

...
[   +1 ms] flutter: Instance of Tor created!
[+4481 ms] Starting proxy!
[   +2 ms] flutter: Done awaiting; tor should be running
[        ] flutter: Starting tor took 4 seconds. Proxy running on port 16217
[+13304 ms] flutter: responseData: {"jsonrpc":"2.0","result":{"hosts":{"horsey.cryptocowboys.net":{"tcp_port":50001,"ssl_port":50002,"ws_port":50003,"wss_port":50004},"qly7g5n5t3f3h23xvbp44vs6vpmayurno4basuu5rcvrupli7y2jmgid.onion":{"tcp_port":50001,"ws_port":50003}},"pruning":null,"server_version":"ElectrumX 1.16.0","protocol_min":"1.4","protocol_max":"1.4.3","genesis_hash":"000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f","hash_function":"sha256","services":["tcp://horsey.cryptocowboys.net:50001","ssl://horse
...

[icota]

@icota, I also have a Monero onion example ready. It's similar so I wondered if it should be included. Let me know if you want that in, as well

Of course, why not? Moneranoj are good people