R1:67b37a5c1dc0

Fix deletion detection when updating based on ZIP

Summary: When the code to update based on ZIP went to look up the child fragments, it explicitly used the paths provided in the ZIP. This meant that we could never detect omissions because there'd never be a scenario where a child fragment would return but not exist in the ZIP. To fix this, the query should be using `withLeadingPath` instead of `withPaths`.

Test Plan: Uploaded a ZIP that omitted a file and saw the `deleteFile` get called (by placing…