convert mobile scanner state to enhanced enum

 /// The authorization state of the scanner.
 enum MobileScannerState {
   /// The scanner has not yet requested the required permissions.
-  undetermined,
+  undetermined(0),
 
   /// The scanner has the required permissions.
-  authorized,
+  authorized(1),
 
   /// The user denied the required permissions.
-  denied
+  denied(2);
+
+  const MobileScannerState(this.rawValue);
+
+  factory MobileScannerState.fromRawValue(int value) {
+    switch (value) {
+      case 0:
+        return MobileScannerState.undetermined;
+      case 1:
+        return MobileScannerState.authorized;
+      case 2:
+        return MobileScannerState.denied;
+      default:
+        throw ArgumentError.value(value, 'value', 'Invalid raw value.');
+    }
+  }
+
+  /// The raw value for the state.
+  final int rawValue;
 }