feat(types): DetectedBarcode improvements

1. Update `detect()` to return a `DetectedBarcode` promise array
2. Update `DetectedBarcode.cornerPoints` to use a tuple and specify that
  `x` and `y` are of type `number`

Author: mfulton26

src/BarcodeDetectorPolyfill.ts

@@ -56,11 +56,11 @@ export class BarcodeDetectorPolyfill {
     /**
      * Scans an image for barcodes and returns a {@link Promise} for the result.
      *
-     * @param {ImageBitmapSource} image the image to be scanned
-     * @returns {Promise<Object>} the scan result as described for {@link BarcodeDetector}
+     * @param {ImageBitmapSource} source the image to be scanned
+     * @returns {Promise<Array<DetectedBarcode>>} the scan result as described for {@link BarcodeDetector}
      */
     // TODO Enable cache for video source, disable for others unless overridden in zbarConfig
-    detect(source: ImageBitmapSource): Promise<Array<Object>> {
+    detect(source: ImageBitmapSource): Promise<Array<DetectedBarcode>> {
         // Return an empty array immediately if the source is an object with any zero dimension,
         // see https://wicg.github.io/shape-detection-api/#image-sources-for-detection
         const intrinsic = BarcodeDetectorPolyfill.intrinsicDimensions(source)

src/DetectedBarcode.ts

@@ -1,10 +1,12 @@
+type Point = { x: number, y: number }
+
 /**
  * @see https://wicg.github.io/shape-detection-api/#detectedbarcode-section
  */
 export interface DetectedBarcode {
 
     boundingBox: DOMRectReadOnly
-    cornerPoints: Array<{ x, y }>
+    cornerPoints: [Point, Point, Point, Point]
     format: string
     rawValue: string