Save config (#345)

* add setters for clients and authorized keys

* impl change config request

* basic saving functionality

* save config automatically

* add TODO comment

lan-mouse-ipc/src/lib.rs

@@ -253,6 +253,8 @@ pub enum FrontendRequest {
     RemoveAuthorizedKey(String),
     /// change the hook command
     UpdateEnterHook(u64, Option<String>),
+    /// save config file
+    SaveConfiguration,
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, Debug, Default, Serialize, Deserialize)]