Add chat message widget

lib/widgets/chat_message.dart

@@ -0,0 +1,18 @@
+import 'package:flutter/widgets.dart';
+
+class ChatMessage extends StatelessWidget {
+  List<InlineSpan> children;
+
+  ChatMessage({Key? key, required this.children}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      child: RichText(
+        text: TextSpan(
+          children: children,
+        ),
+      ),
+    );
+  }
+}