Sort bag by attribute key when using libs

When shared libraries are assigned package ids in a different order
than compile order, bag resources that use attributes from both
multiple libraries will not be sorted in ascending attribute id order.
This change detects when the attribute ids are not in order and sorts
the bag entries accordingly.

The change is designed to be less invasive. Deduping the GetBag logic
should probably be spun off in a separate bug.

Bug: 147674078
Test: libandroidfw_tests
Change-Id: Id8ce8e9c7ef294fcc312b77468136067d392dbd0