Modify the release tag chatops command to also support pages

In order to automatically create tags on the GitLab Pages project as part of our standard release process, we want to modify the chatops command release tag to also support creating the right tag on in the GitLab Pages repository. This issue moves Pages into Managed Versioning.

TODO

• Add a class ReleaseTools::PublicRelease::PagesRelease to perform the following actions gitlab-org/release-tools!2087 (merged)
  • Create a stable branch
  • compile a changelog automatically
  • Update the version file VERSION in the gitlab-pages repo with the new version
  • Create the git tag in the gitlab-pages repo using the last deployment SHA from #2607 (closed)
  • Add the release metadata to https://ops.gitlab.net/gitlab-org/release/metadata
  • Notify slack
• Extend ReleaseTools::Services::SyncRemoteService to also sync GitLab-pages gitlab-org/release-tools!2085 (merged)
• Extend ReleaseTools::Security::SyncRemoteService to also sync GitLab-pages gitlab-org/release-tools!2085 (merged)
• Edit lib/tasks/release.rake to release pages before releasing GitLab
• Modify ReleaseTools::PublicRelease::GitlabRelease to update GITLAB_PAGES_VERSION before tagging gitlab-org/release-tools!2086 (merged)

Definition of Done

• /chatops run release tag <monthly release rc> creates the correct tag on the correct SHA in https://gitlab.com/gitlab-org/gitlab-pages
• GITLAB_PAGES_VERSION in https://gitlab.com/gitlab-org/gitlab is automatically updated as part of the /chatops run release tag process
• /chatops run release tag <monthly release final tag> creates the correct tag on the correct SHA in https://gitlab.com/gitlab-org/gitlab-pages
• /chatops run release tag <patch release> creates the correct tag on the correct SHA in https://gitlab.com/gitlab-org/gitlab-pages
• /chatops run release tag <security release> creates the correct tag on the correct SHA in https://gitlab.com/gitlab-org/gitlab-pages