Output properties before sets in snapshot module

This ensures a consistent output irrespective of whether property sets
are created before or after the properties are added. This provides a
little more flexibility in the creation code which allows that to be
simplfied.

Also switches from using reflection to a type switch.

Bug: 142918168
Test: m nothing
Change-Id: Ia025bfc751f1217d1658de6fb8e15091ea0ea9ff