Refactor system properties protos to just include the list treble team

defines http://go/treble-sysprop-compatibility.

Also refactored system properties proto to have nested proto
definitions. The reason to do it is to have flat proto definition makes
it super hard to manage its field numbers as well as hard to use.
Since we have a predefined list. Support parsing nested proto here.

Bug: 68774852
Test: unit tested and on device test
      $ out/host/linux-x86/bin/incident_report -w system_properties
Change-Id: Icfc7cdcae184fb204c81e6434d21399aa84a1285