feat: Better autoscroll - for #909

[alexhancock]

• Addresses GUI: Goose insists on scrolling to the end, even when you're trying to read the scrollback #909
• Pulls the automatic scrolling logic into the ScrollArea component with an optional autoScroll param to enable this behavior
• Removes associated logic from ChatWindow
• Exposes a scrollToBottom method which parent components can use the programmatically trigger a scroll to the bottom (ChatWindow uses this to always scroll to the bottom when a user sends a message)
• Aways scrolls to the bottom when children of the ScrollArea viewport change if the user was scrolled to the bottom previously
• Temporarily disables auto scroll if the user scrolls away from the bottom