Feature Request: Add Device Preview for Android TV

First of all, thank you for creating and maintaining this incredible package. It has become an essential tool for Flutter mobile development.

My feature request addresses a gap when developing for the **Android TV platform**. While `device_preview` is excellent for checking layouts on different screen sizes, the most critical aspect of TV UI development is **focus handling and D-pad navigation**.

Currently, to test if my UI is navigable with a remote control, I have to:
1. Build the full APK.
2. Deploy it to a physical Android TV or an emulator.
3. Manually test the focus flow with a D-pad.

This process is slow and defeats the purpose of a "live preview", making the development cycle for TV apps much less efficient compared to mobile. While I can add a custom device with a TV's resolution, it doesn't solve the core problem of interaction testing.

I would like to request an enhancement to `device_preview` that introduces **D-pad navigation simulation** for devices, especially for a new "Android TV" device profile.

This could be implemented in a few ways:

1. **A Virtual D-Pad Controller:** Add a small, floating remote control UI within the `device_preview` window. This controller would have buttons for **Up, Down, Left, Right, and Select/Enter**. Clicking these buttons would send the corresponding key events to the Flutter app running in the preview.

2. **Keyboard Passthrough:** Allow the developer's physical keyboard arrow keys (`↑`, `↓`, `←`, `→`) and the `Enter` key to act as a D-pad when the device preview is focused. This would be incredibly intuitive and fast.

3. **Visual Focus Indicator:** The preview should clearly show the standard Flutter focus highlight on the widget that currently has focus as the user navigates with the virtual D-pad or keyboard.

Ideally, there would be a predefined device in the list, such as "Android TV (1080p)", which automatically enables this navigation simulation mode.

The only alternatives are the current, inefficient methods:
* Using a full Android TV emulator: This is very resource-heavy and slow to start and deploy to.
* Using a physical TV: This requires extra hardware and a cumbersome, repetitive deployment process.

Both of these methods take me out of the IDE and break the fast feedback loop that `device_preview` provides so well for mobile.

Implementing this feature would be a game-changer for Flutter developers targeting the living room. It would make `device_preview` a comprehensive tool for virtually all Flutter platforms. The ability to test and refine TV navigation in real-time would dramatically speed up development and encourage the creation of higher-quality, more accessible TV applications with Flutter.

Thank you for your consideration! I believe this would be a highly valuable addition to an already fantastic package.