Schematize Display system properties

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

Bug: 117924132
Test: m -j
Change-Id: If0b7658e4f04848a6a068c18e93026591b7b5518
Merged-In: I83b40ddfcde32d8d03fae73f5c252013933c466c