Bluetooth: HCI: Add option CONFIG_BT_HCI_ACL_DATA_SIZE

Add the option CONFIG_BT_HCI_ACL_DATA_SIZE which allows the user
to configure the max HCI ACL data payload. This is needed for platorms
where the BLE LL, HCI uart and host run on three different cores.

Fixes: #30441

Signed-off-by: Johan Stridkvist <johan.stridkvist@nordicsemi.no>