Add AVCaptureSession/CameraX-based live capture support to SkipAV

[ajayjapan]

Summary

SkipAV currently wraps Jetpack Media3 for playback, but live camera capture/preview via AVCaptureSession is not implemented. Please add
API support to create and run a capture session (front/back camera toggle, preview layer), enabling live camera preview/recording.

Use case

• SwiftUI app needs to show a live camera feed.
• Existing code uses AVCaptureSession + AVCaptureVideoPreviewLayer (example gist: https://gist.github.com/ajayjapan/73231c1df38c620fc6bf89c3a5b036c7).
• Without capture support, the app can’t preview or record video through SkipAV.

Desired behavior

• Provide a cross-platform API in SkipAV to start/stop camera capture and surface a preview surface/view.
• Support selecting front/back cameras and toggling at runtime.
• Expose camera authorization hooks or integrate with the existing permission helpers.
• Ideally support both preview and recording (or at least preview as a first step).

Platform details

• iOS example relies on AVCaptureSession and AVCaptureVideoPreviewLayer.
• Android likely needs CameraX integration to achieve parity.

Additional context

Discussion reference: https://github.com/orgs/skiptools/discussions/551#discussioncomment-15231529
Maintainer suggested filing an enhancement.