Securely encrypt the master key

Move all key management into vold
Reuse vold's existing key management through the crypto footer
to manage the device wide keys

This is one of four changes to enable this functionality:
  https://android-review.googlesource.com/#/c/144586/
  https://android-review.googlesource.com/#/c/144663/
  https://android-review.googlesource.com/#/c/144672/
  https://android-review.googlesource.com/#/c/144673/

Bug: 18151196
Change-Id: I9a162b90afe5f46a4ff15b3878e2ab503795425e
6 files changed