Initial work on GitLab Pages update

Gemfile

Gemfile.lock

app/controllers/projects/pages_controller.rb

app/controllers/projects_controller.rb

app/helpers/projects_helper.rb

app/models/project.rb

app/policies/project_policy.rb

app/services/projects/update_pages_configuration_service.rb

app/validators/certificate_key_validator.rb

app/validators/certificate_validator.rb

app/views/layouts/nav/_project_settings.html.haml

app/views/projects/pages/_access.html.haml

app/views/projects/pages/_destroy.haml

app/views/projects/pages/_disabled.html.haml

app/views/projects/pages/_form.html.haml

app/views/projects/pages/_remove_certificate.html.haml

app/views/projects/pages/_upload_certificate.html.haml

app/views/projects/pages/_use.html.haml

app/views/projects/pages/show.html.haml

app/workers/pages_worker.rb