R1:a72a66caa833

Mark "low importance" and "owned" changes in the filetree

Summary: Ref T13516. Mark low-importance changes (generated code, deleted files) and owned-with-authority changes in the filetree.

Test Plan: {F7375327}

Maniphest Tasks: T13516

Differential Revision: https://secure.phabricator.com/D21157