Initial definition of data types and enumerations for OBD2-compatible diagnostic properties

This commit defines a list of properties that we want to support in VHAL for the purpose
of gathering vehicle diagnostics, and a data structure to contain the values of those
properties in the form of a "snapshot"

It does not yet define the property itself as that relies on a yet undefined hybrid type

Test: build
Change-Id: Ifa5bbf45c4aee2f93cbd82316d3399c04e3c34b4