[Feature] MSG_TYPES in stray_cat should be configurable

[danieledav]

Describe the solution you'd like
MSG_TYPES in stray_cat should be configurable to send custom message types on web socket.

Example:
GOAL: send internal messages to other systems components that the user should not read in chat
SOLUTION: filtering web socket payloads by message type

cat.send_ws_message("Internal message", msg_type="sys_message")

Additional context
Ref. line 23 of core/cat/looking_glass/stray_cat.py
MSG_TYPES = Literal["notification", "chat", "error", "chat_token"]

[pieroit]

Not a priority but a reasonable request; let's keep the issue open to see if more people manifest interest.
Thanks @danieledav