Really set source IP for broadcast discovery packets on Windows/FreeBSD

This whole code was no-op: it enumerates network interfaces, enumerates
its IP addresses, but does not change the address of broadcast UDP
packet, sending it only via default route/interface.

Bind the socket to IP addresses of the interfaces to fix the issue.

BUG: 459171

core/backends/lan/lanlinkprovider.cpp

@@ -171,6 +171,7 @@ void LanLinkProvider::broadcastToNetwork()
                 QHostAddress sourceAddress = ifaceAddress.ip();
                 if (sourceAddress.protocol() == QAbstractSocket::IPv4Protocol && sourceAddress != QHostAddress::LocalHost) {
                     qCDebug(KDECONNECT_CORE()) << "Broadcasting as" << sourceAddress;
+                    sendSocket.bind(sourceAddress);
                     sendBroadcasts(sendSocket, np, destinations);
                     sendSocket.close();
                 }