[Feature]: Add send_message feature to chat dock

[Laurick]

Description

The add_message feature was added to the addon days ago and I think it's a good idea add that fuctionality to the chat dock to be tested and used for everyone

Current Behavior

The feature is not implemented in the chat dock

How

The front can be a line_edit with a button with the new functionality attached to send the message.

Maybe it's a cool idea hide the line edit and the button until its needed to keep the chat/dock clean :)

[rothiotome]

Sounds like a plan! Waiting fot your PR :D