MINOR: stream/cli: use conn_get_{src,dst} in "show sess" and "show peers" output

MINOR: stream/cli: use conn_get_{src,dst} in "show sess" and "show peers" output

The stream outputs requires to retrieve connections sources and
destinations. The previous call involving conn_get_{to,from}_addr()
was missing a status check which has now been integrated with the
new call since these places already handle connection errors there.

The same code parts were reused for "show peers" and were modified
similarly.