feat: Introduce FocusScopeDismissible (#52)

* Introduce BackgroundFocusScopeDismisser

* fix: Rename to FocusScopeDismissible

* fix: Rename the folder to utilities

* feat: Add dragStartBehaviour, excludeFromSemantics

Author: nivisi

lib/presentation/widgets/utilities/focus_scope_dismissible.dart

@@ -0,0 +1,57 @@
+import 'package:flutter/gestures.dart';
+import 'package:flutter/widgets.dart';
+
+/// A widget for dismissing the keyboard on tap outside.
+///
+/// Wrap a widget that contain text inputs with this widget
+/// to enable tap-outside-to-dismiss-keyboard behaviour.
+///
+/// So instead of this:
+///
+/// ```dart
+/// GestureDetector(
+///   onTap: () {
+///      final focusScope = FocusScope.of(context);
+///      if (focusScope.hasFocus) {
+///        focusScope.unfocus();
+///       }
+///   },
+///   child: MyPage(),
+/// ),
+/// ```
+///
+/// You could do this:
+///
+/// ```dart
+/// BackgroundFocusScopeDismisser(
+///   child: MyPage(),
+/// ),
+/// ```
+class FocusScopeDismissible extends StatelessWidget {
+  const FocusScopeDismissible({
+    Key? key,
+    this.excludeFromSemantics = false,
+    this.dragStartBehavior = DragStartBehavior.start,
+    required this.child,
+  }) : super(key: key);
+
+  final DragStartBehavior dragStartBehavior;
+  final bool excludeFromSemantics;
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      dragStartBehavior: dragStartBehavior,
+      excludeFromSemantics: excludeFromSemantics,
+      onTap: () {
+        final focusScope = FocusScope.of(context);
+
+        if (focusScope.hasFocus) {
+          focusScope.unfocus();
+        }
+      },
+      child: child,
+    );
+  }
+}