[Barcode scanner] Allow scanning barcodes with front camera if rear camera is not available

[samiuelson]

There are devices, like Chromebooks that does not have LENS_FACING_BACK camera available.

It would be useful to fall back to fallback to LENS_FACING_BACK in case the first one is not available.

Context/discussion: https://woomobilecuw.wordpress.com/2024/11/26/android-illegalargumentexception-provided-camera-selector-unable-to-resolve-a-camera-for-the-given-use-case/#comment-2709

File: BarcodeScanner.kt

[dangermattic]

🚫 Please add a type label (e.g. type: enhancement) and a feature label (e.g. feature: stats) to this issue.