[Request]: Add support for background activity launch

### Plugin

android_intent_plus

### Use case

targeting Android 15 or higher will default to no longer implicitly granting background activity launch (BAL) privileges to PendingIntents they create. Explicit opt-in is required

due to this activity launch fails without any error, there should be way to opt in for BAL, native android allows it using:

```
val options = ActivityOptions.makeBasic()
options.setPendingIntentBackgroundActivityStartMode(
ActivityOptions.MODE_BACKGROUND_ACTIVITY_START_ALLOW_ALWAYS
)
context.startActivity(intent, options.toBundle())

```

### Proposal

```
final AndroidIntent intent = AndroidIntent(
action: '....',
data: '....',
/// Add option to pass
backgroundActivityStartMode: ActivityOptions.MODE_BACKGROUND_ACTIVITY_START_ALLOWED
);
await intent.launch();
```