CapacitorBarcodeScannerCameraDirection.BACK always uses front camera on Web

As mentioned in the title, I encountered an issue with CapacitorBarcodeScannerCameraDirection.BACK on Web.
Even when explicitly setting it to use the back camera, it still defaulted to the front camera.

I implemented a quick fix inspired by a capacitor-community PR, which successfully resolved the issue in my case.
I’ve already opened a PR for this and I’m waiting for it to be reviewed. I’m open to making any necessary changes to ensure it gets merged as soon as possible.

[PR LINK](https://github.com/ionic-team/capacitor-barcode-scanner/pull/89)

Start by reviewing PR #89, which contains the reported fix, and reproduce the Web behavior with CapacitorBarcodeScannerCameraDirection.BACK. Confirm that Web selects the back camera and check the PR’s validation before making any requested review changes.

Written by the indexing model from the issue text.