Add streaming to exec and tui (#1594)

Added support for streaming in `tui`
Added support for streaming in `exec`


https://github.com/user-attachments/assets/4215892e-d940-452c-a1d0-416ed0cf14eb

codex-rs/tui/src/app.rs

@@ -297,6 +297,8 @@ impl<'a> App<'a> {
     }
 
     fn draw_next_frame(&mut self, terminal: &mut tui::Tui) -> Result<()> {
+        // TODO: add a throttle to avoid redrawing too often
+
         match &mut self.app_state {
             AppState::Chat { widget } => {
                 terminal.draw(|frame| frame.render_widget_ref(&**widget, frame.area()))?;