Bluetooth: SAP: Add 16 digit authentication support for SAP

This change consists of:
16 digit authentication support for SAP

Change-Id: I6488b449a59f90b879fff3c0fe0ca4ecefdc1947
(cherry picked from commit 7b2c37a7c3d0d95558385cc73b039f207834dd93)
(cherry picked from commit 0c28e3643378250a53458b62b33a03b047851b5c)
(cherry picked from commit 753cf921dfc66b6e6700ff59b8754c0a4c01685a)