Encourage creating Binder tokens with a descriptor.

Binder tokens (Binder objects without an attached interface) are used
a lot with Android. These tokens don't have an interface descriptor,
which means that proxies (references) to these tokens are impossible
to identify when looking at a heap dump.

To make that easier, introduce a new constructor for Binder that allows
the caller to specify a descriptor.

Bug: 109888955
Test: builds, boots
Change-Id: I18fd00483abc29edf87f84945323a10fe4f6cd42