Core: CommonClient: command history and echo (#3236)

* client: Added command history access with up/down and command echo in common client

* client: Changed command echo colour to orange

* client: removed star import from typing

* client: updated code style to match style guideline

* client: adjusted ordering of calling parent constructor in command prompt input constructor

* client: Fixed issues identified by beauxq in PR; fixed some typing issues

* client: PR comments; replaced command history list with deque

CommonClient.py

@@ -493,6 +493,11 @@ class CommonContext:
         """Gets called before sending a Say to the server from the user.
         Returned text is sent, or sending is aborted if None is returned."""
         return text
+    
+    def on_ui_command(self, text: str) -> None:
+        """Gets called by kivy when the user executes a command starting with `/` or `!`.
+        The command processor is still called; this is just intended for command echoing."""
+        self.ui.print_json([{"text": text, "type": "color", "color": "orange"}])
 
     def update_permissions(self, permissions: typing.Dict[str, int]):
         for permission_name, permission_flag in permissions.items():