Fix adb backup/restore

* Exclude key/value-only backup participants until we have a chance to
  augment the archive format with proper handling.

* Don't back up 'stopped' apps, which would un-stop them

* Fix unspecified-user bindService/startActivity invocations

* Teach adb restore about the onRestoreFinished() lifecycle method

* Implement proper app timeout handling in the adb data flows

* Backstop wallpaper backup against rare leftover-state issues

Bug 28056941

Change-Id: Ia59c71a2c74a632a2c2a527b9b7374229c440d46