contactadapter: fix SelectableProxyModel ownership

Currently the ownership of SelectableProxyModel instance
is assumed by QML engine, but we will use the following
rule to avoid that.

QML engine respects the normal QObject parent ownership
semantics of Qt C++ objects, and will never delete a
QObject instance which has a parent.

https: //doc.qt.io/qt-5/qtqml-cppintegration-data.html
Change-Id: Ifa37d14b8d74bfce050b0dee2949b42a7f784d3a

src/contactadapter.cpp

@@ -25,7 +25,7 @@
 ContactAdapter::ContactAdapter(LRCInstance* instance, QObject* parent)
     : QmlAdapterBase(instance, parent)
 {
-    selectableProxyModel_.reset(new SelectableProxyModel(smartListModel_.get()));
+    selectableProxyModel_.reset(new SelectableProxyModel(this));
 }
 
 QVariant

src/contactadapter.h

@@ -44,10 +44,9 @@ class SelectableProxyModel final : public QSortFilterProxyModel
 public:
     using FilterPredicate = std::function<bool(const QModelIndex&, const QRegExp&)>;
 
-    explicit SelectableProxyModel(QAbstractListModel* parent = nullptr)
+    explicit SelectableProxyModel(QObject* parent = nullptr)
         : QSortFilterProxyModel(parent)
     {
-        setSourceModel(parent);
         setSortRole(ConversationList::Role::LastInteractionTimeStamp);
         sort(0, Qt::DescendingOrder);
         setFilterCaseSensitivity(Qt::CaseSensitivity::CaseInsensitive);