Specs to verify autolink works as GitLab expects

Update to comrak 0.23.0, which adds some fixes to autolink and relaxed_autolinks options.

Moved specs from GitLab's https://gitlab.com/gitlab-org/gitlab/blob/master/spec/lib/banzai/filter/autolink_filter_spec.rb. This allows us to replace https://gitlab.com/gitlab-org/gitlab/blob/master/lib/banzai/filter/autolink_filter.rb with the native version.

Diff: https://github.com/kivikakk/comrak/compare/0.22.0...0.23.0