Stub out VTS testing for OBD2 sensors

This commit adds support to VHAL for returning a live and a freeze OBD2 frame filled in with default placeholder values
It also adds a VTS test to check for OBD2 support. Doing anything more interesting is currently blocked.

Test: make vts BUILD_GOOGLE_VTS=true -j32 && vts-tradefed run commandAndExit vts --skip-all-system-status-check --primary-abi-only --skip-preconditions --module VehicleHidlTest -l INFO
Change-Id: I4aad71f7bb65a690841e74d06fefc5fb2076ce5e