[TS migration] Migrate killApp from E2E to typescript

tests/e2e/utils/killApp.ts

@@ -0,0 +1,15 @@
+import {MAIN_APP_PACKAGE} from '../config';
+import execAsync from './execAsync';
+
+type KillApp = (platform: string, packageName: string) => Promise<void>;
+
+const killApp: KillApp = function (platform = 'android', packageName = MAIN_APP_PACKAGE) {
+    if (platform !== 'android') {
+        throw new Error(`killApp() missing implementation for platform: ${platform}`);
+    }
+
+    // Use adb to kill the app
+    return execAsync(`adb shell am force-stop ${packageName}`);
+};
+
+export default killApp;