add typing indicator widget

lib/src/typing_indicator.dart

@@ -0,0 +1,26 @@
+import 'package:flutter/material.dart';
+import 'package:stream_chat/stream_chat.dart';
+
+/// Widget to show the current list of typing users
+class TypingIndicator extends StatelessWidget {
+  const TypingIndicator({
+    Key key,
+    @required this.typings,
+    this.style,
+  }) : super(key: key);
+
+  /// Style of the text widget
+  final TextStyle style;
+
+  /// List of typing users
+  final List<User> typings;
+
+  @override
+  Widget build(BuildContext context) {
+    return Text(
+      '${typings.map((u) => u.name).join(',')} ${typings.length == 1 ? 'is' : 'are'} typing...',
+      maxLines: 1,
+      style: style,
+    );
+  }
+}