vault: directory cooker: handle symlinks and executables
Test Plan
With a custom archive: % ls -l total 8 -rwxr-xr-x 1 antoine antoine 11 Feb 17 16:50 executable -rw-r--r-- 1 antoine antoine 8 Feb 17 16:50 realfile lrwxrwxrwx 1 antoine antoine 8 Feb 17 16:50 symlink -> realfile
Migrated from D164 (view on Phabricator)