Bluetooth: TBS: Allow multiple callbacks for client

The TBS client callbacks are just informative so we
provide the information to multiple listeners.

To support this for the long strings, the function
handle_string_long_read was refactored.

This also allows for multiple users of the TBS client.

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