Fix issue #17752399: Multiple apps broken by GET_TASKS permission change

Keep around GET_TASKS as a permission available to apps, so apps still
think they have it and don't get all uppity because they don't.

Add a new REAL_GET_TASKS that is the actual permission now.

Plus some temporary compatibility code until everyone can transition
fromn GET_TASKS to REAL_GET_TASKS.

Change-Id: I12c1102eed24844685dcbd2fa3b612811603958f