Use Virtual Backgrounds with the Agora React Native SDK

The Agora React Native SDK now supports using virtual backgrounds, allowing users to choose a solid color or an image for their background during video calls and live streams. To enable this feature, developers can call the `enableVirtualBackground` method on the engine object with their desired configuration. Two open-source libraries, `react-native-image-picker` and `react-native-fs`, are required to bundle an image asset with React Native and select a user image as a virtual background. The Agora SDK handles tasks such as segmentation and background removal automatically. Developers can also join the Agora Developer Slack community for assistance and further information on available features.