This supersedes any backup-password that the user might supply. Per
design, the device encryption password is also always used to encrypt
the backup archive.
The CL introduces two new strings, used for prompting the user for
their device encryption password rather than their settings-defined
"backup password" when confirming a full backup or restore operation.
Bug 5382487
Change-Id: I0b03881b45437c944eaf636b6209278e1bba7a9f
32418be49e