Schematize Setup Wizard system properties

Properties accessed across partitions are now schematized and will
become APIs to make explicit interfaces among partitions.

Bug: 117924132
Test: mma -j
Change-Id: I3a6c382ceb0de607d3e7d47aaf4093701ae655db
(cherry picked from commit 40a7cba921948b7d30e9fd64306b07948f2c8fe4)