Implement basic chat functionality

rc_chat_room/src/state/chat/mod.rs

@@ -0,0 +1,13 @@
+mod chat;
+pub use chat::{ChatSystem, ChatProvider};
+
+mod room;
+pub use room::ChatRoom;
+
+mod user;
+pub use user::UserHandle;
+
+mod config;
+pub use config::{ChatSystemConfig};
+
+pub type ChatImpl = ChatProvider;