fix(core): cleanup app before exit, closes #2464 (#2466)

.changes/app-handle-exit-cleanup.md

@@ -0,0 +1,5 @@
+---
+"tauri": patch
+---
+
+Cleanup application on `AppHandle#exit`.

core/tauri/src/app.rs

@@ -257,6 +257,7 @@ impl<R: Runtime> AppHandle<R> {
 
   /// Exits the app
   pub fn exit(&self, exit_code: i32) {
+    self.cleanup_before_exit();
     std::process::exit(exit_code);
   }