widget/default_message_widget library

1. xc_chat_scroll_list_view package
2. documentation
3. widget/default_message_widget.dart

xc_chat_scroll_list_view package

1. Libraries
2. chat_message
3. core/chat_controller
4. models/message_model
5. utils/webchat_date_format
6. widget/chat_list_widget
7. widget/default_message_widget