Cache binder calls in CompatChanges

Cached call values are kept in ChangeIdStateCache (per-process cache).
Use "cache_key.is_compat_change_enabled" system property to
invalidate the cache (i.e. any value different from the last observed
will trigger an invalidation).
Any process can read that property, but only system server can change it.

Bug: 140441727
Test: atest PlatformCompatTest
Test: atest CompatConfigTest
Test: atest CompatChanges
Test: atest PlatformCompatGating

Change-Id: Ibed398ae965b7da2432aaf8d5ffc259f7d228c7e