service: Introduce a command-line client

This CL introduces a CLI for the Bluetooth daemon. The code currently
doesn't do much, other than demonstrate how a native Binder client code
can be placed to the Bluetooth daemon. This objective here is to
extend this with a REPL and send commands to the daemon based on user
input.

Bug: 22743129
Change-Id: I41015e4b639e7099dd9f7086dbe86b01f3a61786