GitLab

This includes:
- new types of controlled-setting-indicator for children/supervised users
- corresponding new "controlled-by" strings
- passing the strings through the developerPrivate API, and removing the now-unnecessary installedByCustodian field

BUG=397951

Review URL: https://codereview.chromium.org/1051273002

Cr-Commit-Position: refs/heads/master@{#330928}