Bluetooth: Add configuration to control the dynamic connection callbacks

This commit allows to the user to control the use or not of dynamic
connection callbacks.
The stack is not using the dynamic connection callbacks so they are
only needed if the applications want to use it.
Setting it to true for backwards compatibility.

With dynamic connection callbacks

           FLASH:      176600 B       512 KB     33.68%
             RAM:       27428 B        64 KB     41.85%
        IDT_LIST:          0 GB        32 KB      0.00%

Without dynamic connection callbacks

           FLASH:      176376 B       512 KB     33.64%
             RAM:       27428 B        64 KB     41.85%
        IDT_LIST:          0 GB        32 KB      0.00%

Signed-off-by: Yago Fontoura do Rosario <yafo@demant.com>