binder: fix decoding of vintf stability ParcelableHolder

Unlike the C++ implementation, `ParcelableHolder`s in rust are decoded
into a new object. The new object was losing the original stability
level, always reverting to local stability, so vintf parcelables would
fail the assertion.

We could replicate the C++ implementation, but it would require a lot of
API refactoring and it is easy to mess up. Instead, we make the
stability part of the type. This somewhat matches AIDL, where the
stability is a static annotation on the type containing the
`ParcelableHolder`.

Bug: 366383257
Test: m
Change-Id: Ic4654830d404fbf18046660eeb0129ab8abf7e61