[@nativescript/local-notifications] Scheduling a notification using the "at" property results in the notification being severly late

• Android 13, targeting API level 33
• @nativescript/core 8.5.7
• @nativescript/local-notifications 6.1.1

This has not been tested on iOS yet, but will be soon, and I'll update this issue with the results once that has been done. It has been replicated on both a Samsung phone and tablet.

While trying to make use of the LocalNotifications.schedule() functionality, the notification arrives as expected, but ends up being significantly late. For instance, when trying to schedule a notification a minute into the future:

public async addScheduledNotification(notificationId: string) {
    const notification = NOTIFICATION_TYPES.find((n => n.id == notificationId));
    const targetStart = new Date(new Date().getTime() + 60 * 1000);
    console.log(`target start: ${targetStart}`);
    console.log(`getTime: ${targetStart.getTime()}`);
    console.log(await LocalNotifications.schedule([{
        id: Number.parseInt(notification.id),
        title: 'My App',
        body: notification.body,
        // interval: 'day' as ScheduleInterval,
        channel: 'MyApp',
        priority: 2,
        at: targetStart
    }]));
    console.log(await LocalNotifications.getScheduledIds());
}

Output:

  JS: CONSOLE LOG: target start: Tue Sep 05 2023 21:30:00 GMT-0400 (EDT)
  JS: CONSOLE LOG: getTime: 1693963800000
  JS: CONSOLE LOG: [0]
  JS: CONSOLE LOG: [0]

the notification will arrive about 1 minute and forty five seconds from the time the code runs. I've tried different use cases and the delay can be as large as 15 minutes to an hour. Lowering the delay to ten seconds after the code runs results in it arriving on time. Leaving the at parameter out results in the notification being shown immediately as expected. There doesn't seem to be much of a difference whether the screen is on or off when the notification is supposed to fire. Seeing as the screen is often on and there's still a delay, I don't suspect the issue is due to a battery saver or Doze.

From my reading of the Android documentation and this plugin's source code, exact alarms are being used with RTC_WAKEUP so there shouldn't be much of a delay in the showing of the notification.

首先，使用提供的 JavaScript/TypeScript 排程範例，在 Android 13 上重現延遲，並使用 @nativescript/core 8.5.7 和 @nativescript/local-notifications 6.1.1。比較要求的 at 時間與所回報裝置上的實際送達時間；完成的標準是找出並修正排程延遲，並驗證短間隔和較長間隔下的行為。