feat: handle android back button on android (#1656)

packages/web/src/javascripts/NativeMobileWeb/AndroidBackHandler.tsx

@@ -0,0 +1,22 @@
+type Listener = () => boolean
+type RemoveListener = () => void
+
+export class AndroidBackHandler {
+  private listeners = new Set<Listener>()
+
+  addEventListener(listener: Listener): RemoveListener {
+    this.listeners.add(listener)
+
+    return () => {
+      this.listeners.delete(listener)
+    }
+  }
+
+  notifyEvent() {
+    for (const listener of Array.from(this.listeners).reverse()) {
+      if (listener()) {
+        return
+      }
+    }
+  }
+}