Bluetooth: CAP: Shell: Implement cmd_cap_handover_broadcast_to_unicast

Implement the shell command for handing over broadcast to
unicast. The command supports various configurations.

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