Add progress dialog for booting after an upgrade.

This introduces a new facility for code during the boot process
to display messages to the user through a progress dialog.  This
is only for use when performing longer-than-usual post-upgrade
operations such as running dexopt on applications or upgrading
databases.

Change-Id: I0e78439ccec3850fb67872c22f235bf12a158dae
17 files changed