template editor: add "edit" button and code preview to template page, not tied to a specific version

I'd love to see the source code and edit a template without having to go into the latest version. 
<img width="1131" alt="Screenshot 2023-02-08 at 3 30 40 PM" src="https://user-images.githubusercontent.com/22407953/217655607-68cacde1-74b0-45c5-b8de-4c536bdeaf57.png">
