Adopted Storage support

 -Detects, decrypts, and mounts an adopted SD card if a
  secondary block device is defined (usually mmcblk1)
 -Handles unified storage
 -Displays the adopted storage in MTP along with internal
 -Factory Reset - wiped just like a data media device, we
  retain the keys folder and the storage.xml during a
  factory reset
 -Backup / Restore
 -Disable mass storage when adopted storage is present
 -Read storage nickname from storage.xml and apply it to
  display names in the GUI
 -Read storage.xml and determine what storage location is in
  use for /sdcard and remap accordingly

libgpt_twrp is source code mostly kanged from an efimanager
project. It is GPL v2 or higher, so we will opt for GPL v3.

Change-Id: Ieda0030bec5155ba8d2b9167dc0016cebbf39d55
18 files changed