Improved the CameraX-MLKit sample to read QRCode and Text.

[Riicksouzaa]

Fixed an error when users not grant the permission so app crashes because barcodeScanner is not initialized.

Improved code with a new mlkit so now the camera can track QRcode and Texts. Removed QrCodeDrawable.kt and created BuildRect.kt instead. Improved the request permission to new resultLauncher API.