agent: Create TerminalToolCard and display shell output while it's running (#29546)

Also, don't require a worktree to run the terminal tool.

Release Notes:

- N/A

crates/terminal_view/src/terminal_element.rs

@@ -1036,7 +1036,7 @@ impl InputHandler for TerminalInputHandler {
         cx: &mut App,
     ) {
         self.terminal.update(cx, |terminal, _| {
-            terminal.input(text.into());
+            terminal.input(text);
         });
 
         self.workspace