Schematize Car 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: I203861a78f48529434595c2e923c03d58b7e8299
Merged-In: I203861a78f48529434595c2e923c03d58b7e8299