Need help with Data ValueConvertible

Nobody has claimed this yet.

I'm new to swift, c, c++, and napi. So forgive the noobyness. I need to pass an object containing a Data (https://developer.apple.com/documentation/foundation/data) object from swift to nodejs (passing image data).

End goal would be Data on nodejs side as a byte array/buffer.

```
import NAPI
import NAPIC
import Foundation
import Cocoa

open class ScreenWithScreenshot : NAPI.ValueConvertible {

public let screenshotData : Data
public let screenIndex : Int
public let screenRect : NSRect
public let scale : CGFloat

public required init(_ screenIndex : Int, _ screen : NSScreen, _ screenshotData : Data) {
self.screenIndex = screenIndex
self.screenshotData = screenshotData
self.screenRect = CoordinateHelper.GetQuartzCoordinates(screen)
self.scale = screen.backingScaleFactor
}

public required convenience init(_ env: napi_env, from: napi_value) throws {
fatalError("Not implemented")
}

public func napiValue(_ env: napi_env) throws -> napi_value {

var result: napi_value!
var status: napi_status!

status = napi_create_object(env, &result)
guard status == napi_ok else { throw NAPI.Error(status) }

var screenIndex: napi_value!
status = napi_create_int32(env, Int32(self.screenIndex), &screenIndex)
guard status == napi_ok else { throw NAPI.Error(status) }

status = napi_set_named_property(env, result, "screenIndex", screenIndex)
guard status == napi_ok else { throw NAPI.Error(status) }

status = napi_set_named_property(env, result, "screenRect", try self.screenRect.napiValue(env))
guard status == napi_ok else { throw NAPI.Error(status) }

var scale: napi_value!
status = napi_create_double(env, Double(self.scale), &scale)
guard status == napi_ok else { throw NAPI.Error(status) }

status = napi_set_named_property(env, result, "scale", scale)
guard status == napi_ok else { throw NAPI.Error(status) }

// //struggling here
// var data: napi_value!
// status = napi_set_named_property(env, result, "data", self.screenshotData.bytes
// guard status == napi_ok else { throw NAPI.Error(status) }

return result
}
}
```

Extensions:
```
import NAPI
import NAPIC
import Foundation
import Cocoa

extension NSRect: NAPI.ValueConvertible {
public init(_ env: napi_env, from: napi_value) throws {
fatalError("Not implemented")
}

public func napiValue(_ env: napi_env) throws -> napi_value {
var status: napi_status!
var result: napi_value!

status = napi_create_object(env, &result)
guard status == napi_ok else { throw NAPI.Error(status) }

var x: napi_value!
status = napi_create_double(env, Double(self.minX), &x)
guard status == napi_ok else { throw NAPI.Error(status) }

var y: napi_value!
status = napi_create_double(env, Double(self.minY), &y)
guard status == napi_ok else { throw NAPI.Error(status) }

var width: napi_value!
status = napi_create_double(env, Double(self.width), &width)
guard status == napi_ok else { throw NAPI.Error(status) }

var height: napi_value!
status = napi_create_double(env, Double(self.height), &height)
guard status == napi_ok else { throw NAPI.Error(status) }

status = napi_set_named_property(env, result, "x", x)
guard status == napi_ok else { throw NAPI.Error(status) }

status = napi_set_named_property(env, result, "y", y)
guard status == napi_ok else { throw NAPI.Error(status) }

status = napi_set_named_property(env, result, "width", width)
guard status == napi_ok else { throw NAPI.Error(status) }

status = napi_set_named_property(env, result, "height", height)
guard status == napi_ok else { throw NAPI.Error(status) }

return result
}

}

extension Data {
var bytes : [UInt8] {
return [UInt8](self)
}
}
```

Start with the `ScreenWithScreenshot.napiValue(_:)` implementation and the commented `data` property code, then review the `Data` extension and NAPI value-conversion entry points shown in the issue. Done means the screenshot's Foundation `Data` is exposed on the Node.js side as a byte array or Buffer while the existing screen fields continue to convert correctly.

Written by the indexing model from the issue text.