[notification] Absolutely broken plugin in V2

The notification plugin is absolutely broken (atleast for Android). Here are some of my findings but I'm pretty sure there is a lot more that doesn't work:
- `cancelAll` always throws an error. It just doesn't work.
- `pending` and `active` are always empty. The type for active is incorrect. Not an array, but an object.
- `channels` always gives the permission denied error, even when proper permissions are given.
- Scheduling just doesn't work on Android in a build
- `cancel` gives no indication on wether it succeeded or not.

All these findings apply to an Android 9 and Android 14 phone, one with Chrome Webview, one with Android System Webview.

Reproduction steps aren't necessary, just import and use and they break.