Add maintenance mode lockout during login

rc_core/src/persist/config/cubes_json.rs

@@ -300,6 +300,7 @@ impl <C: Clone + Send> super::ConfigProvider<C> for CubeConfig {
             intercom_url: self.settings.server.intercom_url.trim_end_matches('/').to_owned(),
             minimum_version: self.settings.server.min_version as i32,
             dos_protect: self.settings.server.dos_protection,
+            maintenance_message: self.settings.server.maintenance_message.clone(),
         }
     }
 

rc_core/src/persist/config/traits.rs

@@ -97,6 +97,7 @@ pub struct ServerConfig {
     pub intercom_url: String,
     pub minimum_version: i32,
     pub dos_protect: bool,
+    pub maintenance_message: Option<String>,
 }
 
 pub enum QueueChangeMode {