Allows users with `updateTemplates` permission to select a specific
template version when creating a task.
One of the biggest changes was moving `TaskPrompt` into `modules/task`
and adding a Storybook entry for it. I also moved some stories from
`TasksPage` to simplify its story.
<img width="1208" height="197" alt="Screenshot 2025-10-02 at 12 09 06"
src="https://github.com/user-attachments/assets/b85d2723-bb52-442b-b8eb-36721944a653"
/>
Closes https://github.com/coder/coder/issues/19986