[avfoundation] Add camera specifics to PlatformCameraDescription

[tjamet]

The purpose of this PR is to open a conversation how to better support the various cameras offered by modern platforms.

In particular, starting with the iOS ecosystem offering a wide range of cameras, including cameras with adaptive field of views like AVCaptureDeviceTypeBuiltInDualCamera or AVCaptureDeviceTypeBuiltInTripleCamera.

This PR envisions:

1. Provide as amny infromation as possible to the PlatformCameraDescription objects

Those objects would exclusively act as adaptation layers to provide close to full-feature within dart.

2. Enrich camera_platform_interface with new high level types

The goal would be to support virtual cameras composed of multiple physical ones, simulating a zoom factor.

To support this, the CameraDescription class would accept an optional, nullable, fieldOfViews list accepting an enum similar to:

/// The field of view of a single physical camera
enum CameraLensFieldOfView {
  /// An utra large field of view, typically around 100 degrees or more.
  /// This is the equivalent of a fisheye lens (~10-20mm focal length).
  ultraWide,

  /// A wide field of view, typically around 60 degrees.
  /// This is the equivalent of a ~24-35mm focal length.
  wide,

  /// A standard field of view, typically around 40 degrees.
  /// This is the default field of view for most cameras.
  /// This is the equivalent of a ~50mm focal length.
  standard,

  /// A telephoto field of view, typically around 20 degrees.
  /// This is the equivalent of a ~85-135mm focal length.
  telephoto,

  /// A super telephoto field of view, typically around 10 degrees.
  /// This is the equivalent of a ~200mm focal length or more.
  superTelephoto,
}

class CameraDescription {
  /// Creates a new camera description with the given properties.
  const CameraDescription({
    required this.name,
    required this.lensDirection,
    required this.sensorOrientation,
    this.fieldOfViews,
  });
  final List<CameraLensFieldOfView>? fieldOfViews;

3. Once fieldOfViews is available in the CameraDescription class, cameraDescriptionFromPlatform from avfoundation, should populate the releant field of views, based on the apple documentation:

AVCaptureDeviceTypeBuiltInWideAngleCamera
A built-in wide-angle camera device type.

AVCaptureDeviceTypeBuiltInUltraWideCamera
A built-in camera device type with a shorter focal length than a wide-angle camera.

AVCaptureDeviceTypeBuiltInTelephotoCamera
A built-in camera device type with a longer focal length than a wide-angle camera.

AVCaptureDeviceTypeBuiltInDualCamera
A built-in camera device type that consists of a wide-angle and telephoto camera.

AVCaptureDeviceTypeBuiltInDualWideCamera
A built-in camera device type that consists of two cameras of fixed focal length, one ultrawide angle and one wide angle.

AVCaptureDeviceTypeBuiltInTripleCamera
A built-in camera device type that consists of three cameras of fixed focal length, one ultrawide angle, one wide angle, and one telephoto.

Similarly, all other supported platform should provide the camera field of view, if known

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[tjamet]

Hi!

This PR is the first draft of the idea to enrich camera support.

I think it's going to need discussion, refinement, and fixes.
I am trying to figure out how to handle unit and integration testing for bindings.

Also, I wanted to discuss the idea, and this PR would be a good starting point.