Spooler should not crash if print service config activities are not exported.

1. If a print service does not export its activities for settings and
   adding printers the print spooler ignores them instead of crashing.
   Also if the service is not enabled its activities are now ignored.

2. Added a dedicated permission for a print service to optionally
   protect its settings and add printer activities such that only the
   system can bind to them.

3. Fixed a crash in the print dialog if its content is detached
   from the window and animators are running.

bug:10680224

Change-Id: I20b57d6622a15f9b2352ba78d04c44e67b316a15