Support for Time-Sensitive notifications on iOS 15

## Feature Request

### Plugin

Local Notifications

### Description

Support for Time-Sensitive notifications on iOS 15+. Time-Sensitive notifications allow the developer to schedule notifications that are important to bypass the Focus active mode or the system `Do not disturb` settings.

### Platform(s)

iOS (15.0+)

### Preferred Solution

We should add the new variable `interruptionLevel` inside the `UNMutableNotificationContent`. The `interruptionLevel` variable is an enum with the following values:

```
case passive = 0
The system adds the notification to the notification list without lighting up the screen or playing a sound.

case active = 1
The system presents the notification immediately, lights up the screen, and can play a sound.

case timeSensitive = 2
The system presents the notification immediately, lights up the screen, and can play a sound, but won’t break through system notification controls.

case critical = 3
The system presents the notification immediately, lights up the screen, and bypasses the mute switch to play a sound.
```

Maybe add an interface to be exported through capacitor so that developer can get these allowed values.

Also, developer must enable the correct value in `App.entitlements` for this to work:

```
com.apple.developer.usernotifications.time-sensitive

```

The above should be added to the documentation too.

### Additional Context

Overview:
https://developer.apple.com/videos/play/wwdc2021/10091/

Relevant apple docs:
https://developer.apple.com/documentation/usernotifications/unmutablenotificationcontent
https://developer.apple.com/documentation/usernotifications/unmutablenotificationcontent/3747253-interruptionlevel
https://developer.apple.com/documentation/usernotifications/unnotificationinterruptionlevel