feat: Code Scanner API (#1912)

* feat: CodeScanner JS API

* feat: iOS

* Use guard

* Format

* feat: Android base

* fix: Attach Surfaces

* Use isBusy var

* fix: Use separate Queue

* feat: Finish iOS types

* feat: Implement all other code types on Android

* fix: Call JS event

* fix: Pass codetypes on Android

* fix: iOS use Preview coordinate system

* docs: Add comments

* chore: Format code

* Update CameraView+AVCaptureSession.swift

* docs: Add Code Scanner docs

* docs: Update

* feat: Use lazily downloaded model on Android

* Revert changes in CameraPage

* Format

* fix: Fix empty QR codes

* Update README.md

package/src/CodeScanner.ts

@@ -0,0 +1,62 @@
+/**
+ * The type of the code to scan.
+ */
+export type CodeType =
+  | 'code-128'
+  | 'code-39'
+  | 'code-93'
+  | 'codabar'
+  | 'ean-13'
+  | 'ean-8'
+  | 'itf'
+  | 'upc-e'
+  | 'qr'
+  | 'pdf-417'
+  | 'aztec'
+  | 'data-matrix'
+
+/**
+ * A scanned code.
+ */
+export interface Code {
+  /**
+   * The type of the code that was scanned.
+   */
+  type: CodeType | 'unknown'
+  /**
+   * The string value, or null if it cannot be decoded.
+   */
+  value?: string
+  /**
+   * The location of the code relative to the Camera Preview (in dp).
+   */
+  frame?: {
+    x: number
+    y: number
+    width: number
+    height: number
+  }
+}
+
+/**
+ * A scanner for detecting codes in a Camera Stream.
+ */
+export interface CodeScanner {
+  /**
+   * The types of codes to configure the code scanner for.
+   */
+  codeTypes: CodeType[]
+  /**
+   * A callback to call whenever the scanned codes change.
+   */
+  onCodeScanned: (codes: Code[]) => void
+  /**
+   * Crops the scanner's view area to the specific region of interest.
+   */
+  regionOfInterest?: {
+    x: number
+    y: number
+    width: number
+    height: number
+  }
+}