emulator: cmd_status() using send_packet() for run hooks easily

emulator: cmd_status() using send_packet() for run hooks easily

Now like cmd_command(), cmd_status() directly uses send_packet() instead
of send_event(), consequently cmd_status() must build the hci packet
without help of send_event(). With this change the events sent by
default_cmd() no more use send_event(), who is a good place to run hooks
for BTDEV_HOOK_POST_EVT. And the functions cmd_command() and
cmd_status() can run hooks for BTDEV_HOOK_POST_CMD.