feat: JPEG XL (#2893)

Support the JPEG XL format (.jxl).

JPEG XL is reported as supported by `sharp.format`:

```
jxl: {
  id: 'jxl',
  input: { file: true, buffer: true, stream: true, fileSuffix: [Array] },
  output: { file: true, buffer: true, stream: true }
}
```

Fixes: #2743

mobile/lib/utils/files_helper.dart

@@ -134,6 +134,9 @@ class FileHelper {
       case 'cin':
         return {"type": "image", "subType": "x-phantom-cin"};
 
+      case 'jxl':
+        return {"type": "image", "subType": "jxl"};
+
       default:
         return {"type": "unsupport", "subType": "unsupport"};
     }