当未授予应用后台弹出页面权限时，在后台push新页面（withContainer=true），无法打开

[√] Flutter (Channel stable, 2.5.3, on Microsoft Windows [Version 10.0.19041.388], locale zh-CN)
[!] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
X cmdline-tools component is missing
Run `path/to/sdkmanager --install "cmdline-tools;latest"`
See https://developer.android.com/studio/command-line for more details.
X Android license status unknown.
Run `flutter doctor --android-licenses` to accept the SDK licenses.
See https://flutter.dev/docs/get-started/install/windows#android-setup for more details.
[√] Chrome - develop for the web
[√] Android Studio (version 2020.3)
[√] IntelliJ IDEA Community Edition (version 2020.2)
[√] Connected device (2 available)

Flutter Boost version: `官方 example`

```
InkWell(
child: Container(
padding: const EdgeInsets.all(8.0),
margin: const EdgeInsets.all(8.0),
color: Colors.yellow,
child: Text(
'push new page withContainer',
style: TextStyle(fontSize: 22.0, color: Colors.blue),
)),
onTap: () {
Timer(Duration(seconds: 5), () {
BoostNavigator.instance.pushReplacement('imagepick',
withContainer: withContainer);
});
},
)
```

应用在前台运行时正常，后台运行无法打开。
允许后台弹出页面权限后，正常打开。

Start with the official FlutterBoost example and reproduce the background push using BoostNavigator.instance.pushReplacement with withContainer=true. Compare behavior when the app lacks background page-pop permission versus when that permission is granted; done means the page opens correctly in the background without requiring that permission.

Written by the indexing model from the issue text.