**PLEASE NOTE THAT THIS DIFF AND SUBSEQUENT DIFFS IN THIS STACK WILL NOT BE LANDED UNTIL MORE OF THE REDESIGN IS READY SINCE THIS WILL CAUSE REGRESSIONS IN PROD**
This diff updates the chat thread list ui to match the ui of the new web app redesign. The new chat thread list ui has a border radius on the selected/hovered chat items and the chat items also have a row gap in between each item. Additionally the padding for the create new chat has also been updated. Here are the screenshot of the figma for reference:
{F1026765}
Linear task: https://linear.app/comm/issue/ENG-5970/update-the-ui-for-the-selected-chathovered-chat-thread
Depends on D10528