Update summary
[Unity] The custom authentication and translation features have been added. The namespace has been changed to BackndChat.
[Unreal] The Unreal SDK has been added.
[Platform API] Platform API has been added.
Note on the function changes
All functions in Chat SDK have been changed from "Backend" to "Backnd."
An error will occur if you use the previous functions without modifying them, so please check the modified functions.