Call::terminate: Use sendIq() task instead of manual IQ ack handling

CallPrivate stores all sent jingle requests internally to look for acks
and to trigger forceful termination upon the ack to SessionTerminate.
This commit replaces this by using the newer sendIq() API and a
QXmppTask.

Author: lnjX

src/client/QXmppCall.cpp

@@ -13,6 +13,7 @@
 #include "QXmppConstants_p.h"
 #include "QXmppJingleIq.h"
 #include "QXmppStun.h"
+#include "QXmppTask.h"
 #include "QXmppUtils.h"
 
 #include "StringLiterals.h"
@@ -212,12 +213,6 @@ void QXmppCallPrivate::handleAck(const QXmppIq &ack)
     if (request != requests.end()) {
         // process acknowledgement
         q->debug(u"Received ACK for packet %1"_s.arg(ack.id()));
-
-        // handle termination
-        if (request->action() == QXmppJingleIq::SessionTerminate) {
-            q->terminated();
-        }
-
         requests.erase(request);
     }
 }
@@ -542,9 +537,14 @@ void QXmppCallPrivate::terminate(QXmppJingleIq::Reason::Type reasonType)
     iq.setAction(QXmppJingleIq::SessionTerminate);
     iq.setSid(sid);
     iq.reason().setType(reasonType);
-    sendRequest(iq);
+
     setState(QXmppCall::DisconnectingState);
 
+    manager->client()->sendIq(std::move(iq)).then(q, [this](auto result) {
+        // terminate on both success or error
+        q->terminated();
+    });
+
     // schedule forceful termination in 5s
     QTimer::singleShot(5s, q, &QXmppCall::terminated);
 }