all: split reusable components into workspace crates

utils/src/on_drop_event.rs

@@ -0,0 +1,18 @@
+use {crate::asyncevent::AsyncEvent, std::rc::Rc};
+
+#[derive(Default)]
+pub struct OnDropEvent {
+    ae: Rc<AsyncEvent>,
+}
+
+impl OnDropEvent {
+    pub fn event(&self) -> Rc<AsyncEvent> {
+        self.ae.clone()
+    }
+}
+
+impl Drop for OnDropEvent {
+    fn drop(&mut self) {
+        self.ae.trigger()
+    }
+}