Simplify Connector class APIs and hierachy

Test: Build; unit tests `atest
 packages/services/Car/tests/vehiclehal_test/src/com/android/car/vehiclehal/test/CarPropertyTest.java`

Bug: b/141493212

Change-Id: I6c561d517646760dfff63cb6c6b50c3c5994098a
5 files changed