FsCrypt.cpp: Do delayed restorecon on /data/vendor_ce

When Android boots after file_contexts has changed, the boot process
walks the entire /data partition, updating any changed SELinux labels as
appropriate. However, credential encrypted ("ce") directories are
deliberately excluded from this early boot directory walk. Files within
ce directories have their filenames encrypted, and as a result, cannot
match the file_contexts entries. Only after the user has unlocked their
device are the unencrypted filenames available and a restorecon
appropriate.

Ensure that we do a post-unlock restorecon on /data/vendor_ce, like we
do for /data/system_ce and /data/misc_ce. This ensures the labels on
files within these directories are correct after the device has been
unlocked.

Bug: 132349934
Test: See bug 132349934 comment #12 for test procedure
Change-Id: Ifcbef5fdfb236ec6dea418efa9d965db3a3b782f