Add a setting to show time to first window draw and frames per second in status bar

[nathansobo]

I want to showcase Zed's performance via videos, and this seemed like a good way to demonstrate it.

https://github.com/user-attachments/assets/f4a5fabc-efe7-4b48-9ba5-719882fdc856

Release Notes:

• On macOS, you can now set assign performance.show_in_status_bar: true in your settings to show the time to the first window draw on startup and then current FPS of the containing window's renderer.