samples: Bluetooth: BAP: Unicast: Print CIG and CIS IDs

Update the unicast client and server samples to use
bt_iso_chan_get_info to get the CIG and CIS IDs of a
BAP stream.

The samples show how it is possible to get the information early
as the unicast client (it is possible right after the stream
has been added to a group), and how the values are only
available to the server once the CIS is connected, which
is indicated by the stream_started callback.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>