fix(DuoChat): Stick to bottom of history while streaming answers

What does this MR do?

Browsers a are pretty good at keeping the focus on an element while the parent element grows in size. With this we mark all child elements of the chat history as "non" anchors.

Right at the bottom of the chat history we add a scroll-anchor element. This scroll-anchor element is the only "possible" anchor. The beauty of it: It only will be used as an anchor if it is it is currently inside the view port.

So if the user manually scrolls up while a chunked message is coming in, it won't stick to the bottom while the message still loads.

See: https://developer.mozilla.org/en-US/docs/Web/CSS/overflow-anchor

Screenshots or screen recordings

video1512974737

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