Built-in auto-response/banner for chat

[Bossett]

Is your feature request related to a problem? Please describe.

A very common use-case when providing support/etc. is to display a single banner or initial chat that directs people to correct resources. e.g. "for tech support contact support@... etc.", or "if this is sensitive my Signal username is...". It would be great if this could be built into the chat system to remove the need for bots, etc.; especially in cases where DMs are closed (i.e. could display this banner in the 'start a chat' pane).

Describe the solution you'd like

A user-editable short status that displays as a banner when initiating or attempting to initiate a chat, and displays at the top under the user header in existing chats.

Describe alternatives you've considered

Probably the nearest alternative would be running a chat bot that just auto-replied like this to all new chats, but it doesn't address things like existing chats, or accounts that want DMs closed. This roughly mirrors a status message you would see in something like Teams/Slack/etc.