Add sleep_on_start option

src/config.rs

@@ -99,6 +99,9 @@ pub struct Server {
     /// Ingress address.
     #[serde(alias = "address_ingress")]
     pub address: SocketAddr,
+
+    /// Immediately start sleeping when starting lazymc.
+    pub sleep_on_start: bool,
 }
 
 /// Time configuration.