Add new "shell command" feature to Binder objects.

IBinder has a new common interface for sending shell commands
to it.  This can be implemented by system services to provide
a shell interface to the service, without needing to have separate
shell java code.

This includes changes to DeviceIdleController to implement the
shell interface for all of the commands it has been providing
through dumpsys.

Change-Id: I76518ea6719d1d08a8ad8722a059c7f5fd86813a