Schematize Telephony System Properties

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

Bug: 117924132
Bug: 141246285
Test: lunch blueline-userdebug; m checkbuild
Change-Id: Ibeba0a11ae553674dec2adaabed50fca23e59c2f
Merged-In: Ie33d165cf47cb1c8a53a7b7387c90231f6cba86c