Add an ssh_arguments configuration file field (#211)

Can be used to add SSH command-line arguments like `-o
ConnectTimeout=2`

src/main.rs

@@ -132,7 +132,14 @@ fn run() -> Result<(), Error> {
                 execute(
                     &mut report,
                     remote_topgrade,
-                    || generic::run_remote_topgrade(run_type, remote_topgrade, config.run_in_tmux()),
+                    || {
+                        generic::run_remote_topgrade(
+                            run_type,
+                            remote_topgrade,
+                            config.ssh_arguments(),
+                            config.run_in_tmux(),
+                        )
+                    },
                     config.no_retry(),
                 )?;
             }