[app_usage: ^2.0.0] The appName is not displayed correctly

### Describe the bug
The getter `appName` supposed to return the name of the app but it returns the last part of the `packageName`

### To Reproduce
```
List infos = await AppUsage.getAppUsage(DateTime.now(), DateTime.now());
print(infos[0].appName);
```

### Expected behavior
For example, consider the app PUBG Mobile
its packageName is `com.pubg.imobile`
`appName` should return PUBG Mobile

### Actual behavior
But `appName` returns imobile

### Screenshots