Add config.x_vt option (fixes #910)

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/main.zig

@@ -1086,6 +1086,7 @@ pub fn main() !void {
                             .setup_cmd = config.setup_cmd,
                             .login_cmd = config.login_cmd,
                             .x_cmd = config.x_cmd,
+                            .x_vt = config.x_vt,
                             .session_pid = session_pid,
                         };