feat: add InstabugWidget for error handling in Flutter apps

- Introduced `InstabugWidget` to wrap the root of the application, providing custom error handling for both Flutter and platform errors.
- Implemented error reporting to Instabug with options for user-defined error handlers.
- Ensured that any exceptions in custom handlers are logged without disrupting Instabug's reporting functionality.

Author: MoKamall

lib/src/utils/instabug_widget.dart

@@ -0,0 +1,125 @@
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:instabug_flutter/src/modules/crash_reporting.dart';
+import 'package:instabug_flutter/src/utils/instabug_logger.dart';
+
+class InstabugWidget extends StatefulWidget {
+  final Widget child;
+
+  /// Custom handler for Flutter errors.
+  /// 
+  /// This callback is called when a Flutter error occurs. It receives a
+  /// [FlutterErrorDetails] object containing information about the error.
+  /// 
+  /// Example:
+  /// ```dart
+  /// InstabugWidget(
+  ///   flutterErrorHandler: (details) {
+  ///     print('Flutter error: ${details.exception}');
+  ///     // Custom error handling logic
+  ///   },
+  ///   child: MyApp(),
+  /// )
+  /// ```
+  /// 
+  /// Note: If this handler throws an error, it will be caught and logged
+  /// to prevent it from interfering with Instabug's error reporting.
+  final Function(FlutterErrorDetails)? flutterErrorHandler;
+  
+  /// Custom handler for platform errors.
+  /// 
+  /// This callback is called when a platform error occurs. It receives the
+  /// error object and stack trace.
+  /// 
+  /// Example:
+  /// ```dart
+  /// InstabugWidget(
+  ///   platformErrorHandler: (error, stack) {
+  ///     print('Platform error: $error');
+  ///     // Custom error handling logic
+  ///   },
+  ///   child: MyApp(),
+  /// )
+  /// ```
+  /// 
+  /// Note: If this handler throws an error, it will be caught and logged
+  /// to prevent it from interfering with Instabug's error reporting.
+  final Function(Object, StackTrace)? platformErrorHandler;
+
+  /// This widget is used to wrap the root of your application. It will automatically
+  /// configure both FlutterError.onError and PlatformDispatcher.instance.onError handlers to report errors to Instabug.
+  /// 
+  /// Example:
+  /// ```dart 
+  /// MaterialApp(
+  ///   home: InstabugWidget(
+  ///     child: MyApp(),
+  ///   ),
+  /// )
+  /// ```
+  /// 
+  /// Note: Custom error handlers should be provided to handle errors before they are reported to Instabug.
+  const InstabugWidget({
+    Key? key,
+    required this.child,
+    this.flutterErrorHandler,
+    this.platformErrorHandler,
+  }) : super(key: key);
+
+  @override
+  State<InstabugWidget> createState() => _InstabugWidgetState();
+}
+
+class _InstabugWidgetState extends State<InstabugWidget> {
+  @override
+  void initState() {
+    super.initState();
+    _setupErrorHandlers();
+  }
+
+  void _setupErrorHandlers() {
+    FlutterError.onError = (FlutterErrorDetails details) {
+      // Call user's custom handler if provided
+      if (widget.flutterErrorHandler != null) {
+        try {
+          widget.flutterErrorHandler!(details);
+        } catch (e) {
+          InstabugLogger.I.e(
+            'Custom Flutter error handler failed: $e',
+            tag: 'InstabugWidget',
+          );
+        }
+      }
+
+      CrashReporting.reportCrash(
+        details.exception,
+        details.stack ?? StackTrace.current,
+      );
+
+      FlutterError.presentError(details);
+    };
+
+    PlatformDispatcher.instance.onError = (Object error, StackTrace stack) {
+      // Call user's custom handler if provided
+      if (widget.platformErrorHandler != null) {
+        try {
+          widget.platformErrorHandler!(error, stack);
+        } catch (e) {
+          InstabugLogger.I.e(
+            'Custom platform error handler failed: $e',
+            tag: 'InstabugWidget',
+          );
+        }
+      }
+
+      CrashReporting.reportCrash(error, stack);
+
+      return true;
+    };
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return widget.child;
+  }
+}