use command chip

Author: renefloor

packages/stream_chat_flutter/lib/src/components/message_composer/stream_chat_message_composer.dart

@@ -307,6 +307,8 @@ class DefaultStreamChatMessageComposer extends StatelessWidget {
                 controller: inputController.textFieldController,
                 placeholder: props.placeholder,
                 focusNode: props.focusNode,
+                command: inputController.message.command,
+                onDismissCommand: () => inputController.command = null,
               ),
               if (props.canAlsoSendToChannel)
                 DmCheckboxListTile(

packages/stream_chat_flutter_core/lib/src/stream_message_input_controller.dart

@@ -182,7 +182,7 @@ class StreamMessageInputController extends ValueNotifier<Message> {
   }
 
   /// Sets a command for the message.
-  set command(String command) {
+  set command(String? command) {
     // Setting the command should also clear the text and attachments.
     message = message.copyWith(
       text: '',