Delete Chat

[teresaqhoang]

Motivation and Context

This PR enables chat deletion. For V1, any user is able to delete any chat they're a part of. This will delete the chat for all participants, including Chat Copilot, as well as all related resources (memories, messages, etc.).

Description

When a chat is deleted,

• It will be immediately removed for the user who initiated the deletion.

• If the chat was a multi-user chat, the chat will be disabled in current session. This allows other participants to save any resources before the chat is wiped out. On refresh, chat is removed from list.

• If the chat was the last chat in the user's current session, a new chat will automatically be created to populate the chat list.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines and the pre-submission formatting script raises no violations
  - [ ] All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

Discussed offline and got sign-off after I addressed his last comments. Ben's oof now for the week, don't want to block