Bluetooth: CAP: Shell: Handover broadcast to unicast

Implement the broadcast to unicast shell command.
It is currently limited to cases with
- 1 connection and multiple streams
- Multiple connections and 1 stream
- Equal amount of streams and connections

Cases with e.g. 3 connections and 2 streams,
or vice versa, are not support given the complexity
of these cases.

Signed-off-by: Emil Gydesen <[email protected]>

Author: Thalley