Only show breadcrumbs for terminals when there's a title (#20997)

Closes https://github.com/zed-industries/zed/issues/20475

Release Notes:

- Fixed terminal title and breadcrumbs behavior

---------

Co-authored-by: Thorsten Ball <thorsten@zed.dev>

assets/settings/default.json

@@ -847,8 +847,12 @@
       }
     },
     "toolbar": {
-      // Whether to display the terminal title in its toolbar.
-      "title": true
+      // Whether to display the terminal title in its toolbar's breadcrumbs.
+      // Only shown if the terminal title is not empty.
+      //
+      // The shell running in the terminal needs to be configured to emit the title.
+      // Example: `echo -e "\e]2;New Title\007";`
+      "breadcrumbs": true
     }
     // Set the terminal's font size. If this option is not included,
     // the terminal will default to matching the buffer's font size.