Move Code Graph teams according to FY22Q3 reorg and create org page

Created by: felixfbecker

This creates a folder and basic index page for the Code Graph org reflecting last week's reorg.

I did not yet delete the developer-insights folder because there is quite a bit of content there that I think would be worth adding to general handbook pages, and pages for the other orgs don't exist yet so it would be a lot of work to do this for all new orgs and teams. I only moved the code-insights team out of it and moved all the Code Graph teams together. I did add a note though that there is a migration in progress.

I added redirects for all pages so no links should be broken.

I added a basic mission statement taken from the reorg document that serves as the index listing all teams & linking out to them.

Also updated every place that referenced the teams or the new org (without linking to it yet) and even some old places that had outdated info.