Following agreement with Lauren from buyer experience I've recreated the
vision page in the new handbook site.  As the original page was deleted
I'm unable to get the history for this page.

I've also added a new include to retain the sales links at the bottom of
the page to point back to the free trial option and about.gitlab.com/sales.

The vision pages are controlled by Buyer expereicne and as such lives on
the about site but its valulable content for the Handbook as well.  To
that end the included shortcode gets the content from Buyer Expereicne
and builds a standard page based on the markdown in the Yaml file.

We stick to a single source of truth being the version in Buyer
experience.  We'll chase any breaking changes they make to the yaml
file.

Brings over the changes from MRs:

* gitlab-com/www-gitlab-com!128330
* gitlab-com/www-gitlab-com!128605

- /content/handbook/company/summit/_index.md
- /content/handbook/company/summit/leadership.md
- /content/handbook/company/summit/unconference.md

This MR marks all those working groups which are currently active with a
status in their frontmatter.  This will allow us to move from manually
updated list of active and past working groups to one we generate
automatically.