feat: Maintain Scroll Position When Closing a Thread

[Abbas-Askari]

Description

Currently, when a user closes a thread, they are taken to the top of the MessageList, which causes them to lose their previous scroll position. Instead, the expected behavior is that the user should remain at the ThreadMainMessage when they close the thread.

As an EmbeddedChat Developer

I need to: Maintain the user's scroll position at the ThreadMainMessage when they close a thread.
So that: The user does not get scrolled to the top of all currently loaded messages and can continue their conversation seamlessly.

Acceptance Criteria

• When a thread is closed, the scroll position should remain at the ThreadMainMessage.