Start on adding support for editing via the assistant panel (#14795)

Note that this shouldn't have any visible user-facing behavior yet. The
feature is incomplete but we wanna merge early to avoid a long-running
branch.

Release Notes:

- N/A

---------

Co-authored-by: Nathan <nathan@zed.dev>

crates/tasks_ui/src/lib.rs

@@ -340,7 +340,7 @@ mod tests {
             workspace
                 .update(cx, |workspace, cx| {
                     // Now, let's switch the active item to .ts file.
-                    workspace.activate_item(&editor1, cx);
+                    workspace.activate_item(&editor1, true, true, cx);
                     task_context(workspace, cx)
                 })
                 .await,