Added SNI option for TLS connections

Disabled by default, add `"sni": true,` to pool config to enable it.

src/base/net/stratum/Client.cpp

@@ -589,7 +589,7 @@ void xmrig::Client::handshake()
     if (isTLS()) {
         m_expire = Chrono::steadyMSecs() + kResponseTimeout;
 
-        m_tls->handshake();
+        m_tls->handshake(m_pool.isSNI() ? m_pool.host().data() : nullptr);
     }
     else
 #   endif