Add intent wedge scanner, MDM support for Android (#863)

Add Android intent wedge scanner support with auto configuration for supported Zebra and Datalogic devices.
Intent wedge scans can be done without pressing the scan button first.

Adds the ability for an MDM server to push settings on Android.

lib/barcode/intent_controller.dart

@@ -0,0 +1,154 @@
+import "dart:async";
+
+import "package:flutter/material.dart";
+import "package:flutter/services.dart";
+import "package:flutter_tabler_icons/flutter_tabler_icons.dart";
+import "package:inventree/app_colors.dart";
+import "package:inventree/barcode/controller.dart";
+import "package:inventree/barcode/handler.dart";
+import "package:inventree/l10.dart";
+import "package:inventree/widget/progress.dart";
+
+bool intentScannerActive = false;
+
+final Stream<dynamic> datawedgeStream = const EventChannel(
+  "inventree/datawedge_scans",
+).receiveBroadcastStream();
+
+class IntentBarcodeController extends InvenTreeBarcodeController {
+  const IntentBarcodeController(
+    BarcodeHandler handler, {
+    super.key,
+    this.initialBarcode,
+  }) : super(handler);
+
+  final String? initialBarcode;
+
+  bool get isBackgroundScan => (initialBarcode ?? "").isNotEmpty;
+
+  @override
+  State<StatefulWidget> createState() => _IntentBarcodeControllerState();
+}
+
+class _IntentBarcodeControllerState extends InvenTreeBarcodeControllerState {
+  StreamSubscription<dynamic>? _sub;
+
+  bool canScan = true;
+  bool get scanning => mounted && canScan;
+
+  bool get isBackgroundScan =>
+      (widget as IntentBarcodeController).isBackgroundScan;
+
+  @override
+  void initState() {
+    super.initState();
+    intentScannerActive = true;
+
+    if (isBackgroundScan) {
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        handleBackgroundScan(
+          (widget as IntentBarcodeController).initialBarcode ?? "",
+        );
+      });
+
+      return;
+    }
+
+    _sub = datawedgeStream.listen((event) {
+      if (!scanning) return;
+
+      if (event is Map) {
+        final map = Map<String, dynamic>.from(event);
+        final data = (map["data"] ?? "").toString();
+        if (data.isNotEmpty) {
+          handleBarcodeData(data);
+        }
+      } else if (event is String && event.isNotEmpty) {
+        handleBarcodeData(event);
+      }
+    });
+  }
+
+  Future<void> handleBackgroundScan(String barcode) async {
+    if (!mounted || barcode.isEmpty) return;
+
+    final NavigatorState navigator = Navigator.of(context);
+    final ModalRoute<dynamic>? route = ModalRoute.of(context);
+
+    showLoadingOverlay();
+
+    try {
+      await widget.handler.processBarcode(barcode);
+    } finally {
+      hideLoadingOverlay();
+
+      if (route != null && route.isActive) {
+        navigator.removeRoute(route);
+      }
+    }
+  }
+
+  @override
+  void dispose() {
+    intentScannerActive = false;
+    _sub?.cancel();
+    _sub = null;
+    super.dispose();
+  }
+
+  @override
+  Future<void> pauseScan() async {
+    if (!mounted) return;
+    setState(() {
+      canScan = false;
+    });
+  }
+
+  @override
+  Future<void> resumeScan() async {
+    if (!mounted) return;
+    setState(() {
+      canScan = true;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (isBackgroundScan) {
+      return const AbsorbPointer(child: SizedBox.expand());
+    }
+
+    return Scaffold(
+      appBar: AppBar(title: Text(L10().scanBarcode)),
+      backgroundColor: Colors.black.withValues(alpha: 0.9),
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            const Spacer(flex: 5),
+            const Icon(TablerIcons.barcode, size: 64),
+            const Spacer(flex: 5),
+            SizedBox(
+              width: 64,
+              height: 64,
+              child: CircularProgressIndicator(
+                color: scanning ? COLOR_ACTION : COLOR_PROGRESS,
+              ),
+            ),
+            const Spacer(flex: 5),
+            Padding(
+              padding: const EdgeInsets.all(20),
+              child: Text(
+                widget.handler.getOverlayText(context),
+                style: const TextStyle(
+                  fontWeight: FontWeight.bold,
+                  color: Colors.white,
+                ),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}