More device-encrypted directory work.

Unify package directory creation logic, and always create user_de
directories to be ready for emulation mode.  Also clean up the new
user_de directories on user deletion, package uninstallation, and
data clearing.  Also run restorecon over the new user_de paths.

Bug: 22358539
Change-Id: I65ab1562db8455dae6e99dbd8965409b1bf3c6b0