**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 thread top bar ui to match the ui of the new web app redesign. This component will be used as the panel header for the message list panel item. For context here is the figma screenshot for reference:
{F1029866}
Linear task: https://linear.app/comm/issue/ENG-5973/update-the-message-list-header-ui