Apply GitLab UI button styles to buttons in app/views/projects/pages directory

Instructions

For instructions about how to apply GitLab UI button styles to the button instances on these templates, see the epic &4001 (closed).

Files in directory with buttons that needs migration

• app/views/projects/pages/_destroy.haml
• app/views/projects/pages/_list.html.haml
• app/views/projects/pages/show.html.haml