Add keepAliveBinder argument to setRpcClientDebug.

When the given binder object dies, the corresponding
RpcServer is also shut down.

This CL does not make use of the argument other than
null checks. See follow-up CL for implementation.

Test: binderLibTest
Bug: 182914638
Change-Id: Id787e70f885b165db703e7bb6fa01e6bec271fe6