Specify that a read_write property can be read only in HAL

Not all read_write properties are included. For example, properties
not exposed through CarPropertyManager are not included. The only
other exception is HVAC_TEMPERATURE_VALUE_SUGGESTION because it behaves
like a function call so it needs to be writable.

Bug: 195962745
Test: presubmit
Change-Id: Ief758fd45b7d21ba2d81899d5bb056c3bc24b15b