Support canceling file transfer from pseudo job

Allows to click cancel on the job popup rather than only from
within NeoChat.

src/filetransferpseudojob.cpp

@@ -12,6 +12,7 @@ FileTransferPseudoJob::FileTransferPseudoJob(Operation operation, const QString
     , m_eventId(eventId)
     , m_operation(operation)
 {
+    setCapabilities(KJob::Killable);
 }
 
 void FileTransferPseudoJob::fileTransferProgress(const QString &id, qint64 progress, qint64 total)
@@ -58,3 +59,9 @@ void FileTransferPseudoJob::start()
                        {i18nc("The URL being downloaded/uploaded", "Source"), m_path},
                        {i18nc("The location being downloaded to", "Destination"), m_path});
 }
+
+bool FileTransferPseudoJob::doKill()
+{
+    Q_EMIT cancelRequested(m_eventId);
+    return true;
+}