Apply GitLab UI button styles to app/views/projects directory

What does this MR do?

Adds @garybell s changes from !50114 (closed)

I moved the changes to this MR as that MR had some pipeline issues related to the fork @garybell was using. Please see that MR for the original discussion.

File	Before	After
app/views/projects/_home_panel.html.haml	Unable to keep open long enough	unable to keep open long enough
app/views/projects/_last_push.html.haml
app/views/projects/_new_project_fields.html.haml
app/views/projects/_readme.html.haml Removed from MR	Unable to find where this button is	Unable to find button
app/views/projects/_service_desk_settings.html.haml
app/views/projects/_stat_anchor_list.html.haml	Unable to find button	Unable to find button
app/views/projects/_visibility_modal.html.haml	modal wouldn't show	modal wouldn't show
app/views/projects/_wiki.html.haml	Not sure the button is the one on an empty wiki	Not sure the button is the one on an empty wiki
app/views/projects/no_repo.html.haml Removed from MR	Unable to find changed buttons	Unable to find changed buttons
app/views/projects/edit.html.haml (overall)
app/views/projects/edit.html.haml (export)
app/views/projects/edit.html.haml (edit merge request)
app/views/projects/edit.html.haml (run housekeeping)
app/views/projects/edit.html.haml (visibility)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done