DO NOT MERGE : Move some system services to their own sub package.

(Cherry pick from master)

As a next step they can be moved into separate directories to be
built as separate modules that may or may not be included in a
particular configuration.

Moves AppWidgetService, BackupManagerService, ClipboardService, DevicePolicyMS,
and WallpaperMS.

Change-Id: Idd92871c1828bdde81d85fe99a9c87a22d53169d