libprocessgroup: add support to set aggregate profiles

To support setting multiple profiles with one call. The json format
is as below example.

  "AggregateProfiles": [
    ...
    {
      "Name": "SCHED_SP_BACKGROUND",
      "Profiles": [ "HighEnergySaving", "LowIoPriority", "TimerSlackHigh" ]
    },
    ...
  }

Bug: 139521784
Test: SetProfile works as expected
Change-Id: Ibe14ed57d5169cafcbcbbdb054df3ed171a2f6a2