Add (un)linkToDeath support to HwBinder.

This is mostly copied over from binder's existing
death recipient support. The implementation keeps
a list of registered recipients, both for being
able to map a native recipient back to the corresponding
Java recipient, as well as being able to unregister
recipients correctly.

Test: mma, hidl_test_java
Bug: 31632518
Change-Id: Id313fd248be6925056c4ade8298fe5fb04e007cc