Bluetooth: Split bt_iso_qos into dedicated structures

Split bt_iso_qos into dedicated unicast and broadcast
structures and add additional broadcast parameters.

Fixes: eca0ae4a ("Bluetooth: Add initial implementation of BIS connections")
Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>