Add ConfigLoaded event to IPC, option to disable built-in notification (#1829)

* feat: config reload ipc event

* cleanups

* Rename and move the new config option

* rename to ConfigLoaded and emit at connection

---------

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

niri-config/src/lib.rs

@@ -60,6 +60,8 @@ pub struct Config {
     #[knuffel(child, default)]
     pub hotkey_overlay: HotkeyOverlay,
     #[knuffel(child, default)]
+    pub config_notification: ConfigNotification,
+    #[knuffel(child, default)]
     pub animations: Animations,
     #[knuffel(child, default)]
     pub gestures: Gestures,
@@ -1047,6 +1049,12 @@ pub struct HotkeyOverlay {
     pub hide_not_bound: bool,
 }
 
+#[derive(knuffel::Decode, Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub struct ConfigNotification {
+    #[knuffel(child)]
+    pub disable_failed: bool,
+}
+
 #[derive(knuffel::Decode, Debug, Default, Clone, Copy, PartialEq, Eq)]
 pub struct Clipboard {
     #[knuffel(child)]
@@ -4769,6 +4777,9 @@ mod tests {
                 skip_at_startup: true,
                 hide_not_bound: false,
             },
+            config_notification: ConfigNotification {
+                disable_failed: false,
+            },
             animations: Animations {
                 off: false,
                 slowdown: FloatOrInt(