Feature/tcp client connection timeout (#176)

* Added timeout values to configs

* Fixed possible crash when using delay larger than 2 years

* Connection timeout with hardcoded value

* Using provided timeout value

* tcp client requiring timeout value at construction

* Client using updated tcp client

* Mixnode using updated tcp client

* Healthchecker having separate timeout + new client config field

* Updated validator with connection timeout field

* Added connection_timeout to validator config template

mixnode/src/node/mod.rs

@@ -95,6 +95,7 @@ impl MixNode {
                 packet_forwarding::PacketForwarder::new(
                     self.config.get_packet_forwarding_initial_backoff(),
                     self.config.get_packet_forwarding_maximum_backoff(),
+                    self.config.get_initial_connection_timeout(),
                 )
             })
             .start(self.runtime.handle())

mixnode/src/node/packet_forwarding.rs

@@ -14,10 +14,12 @@ impl PacketForwarder {
     pub(crate) fn new(
         initial_reconnection_backoff: Duration,
         maximum_reconnection_backoff: Duration,
+        initial_connection_timeout: Duration,
     ) -> PacketForwarder {
         let tcp_client_config = multi_tcp_client::Config::new(
             initial_reconnection_backoff,
             maximum_reconnection_backoff,
+            initial_connection_timeout,
         );
 
         let (conn_tx, conn_rx) = mpsc::unbounded();