VehicleHal::set() should not be able to tamper with a property's AVAILABLE status

Properties being (UN)AVAILABLE is used as a one-way communication mechanism from the hardware
to the operating system, and not viceversa.

Add safety checks in our default HAL implementation to:
  - prevent Android from marking a property as UNAVAILABLE;
  - prevent Android from writing to an UNAVAILABLE property.

The combined effect of these two check is that only AVAILABLE properties are writable,
and they can never be flipped to UNAVAILABLE outside of the HAL implementation itself.

Bug: 74805437
Test: manual
Change-Id: Ib830427d604579015fa142f0fa76f8b73a68a452