Migrate data files from www to own repo

Migrate all files that are required for handbook and team page to its own repository.

Both www-gitlab-com and handbook repositories (currently used as part of build of data/public) should sync the data from the new data repository.

Considerations:

1. codeowners be part of this move. Then have codeowners in public/internal handbook repos sync the one file.
2. How review apps will work when data files are being updated. Different review app job depending on which data files are being edited?

Additional requirements:

1. Documentation on basic usage, structure should be added to readme.
2. Data files should have link to original placement of files, meaning 'where to edit'.
3. 'How to edit team page' should be updated. Can ask @cynthia to do when ready.

Concerns about having a unified CODEOWNERS for public/internal handbook:

1. Unclear which repository a given entry is for. Would we enforce a comment that notes which repository an entry is for?
2. Directory structure is likely to diverge between public and internal handbooks
3. There could be a page in the public and internal handbooks with the same path but different ownership desired