EffectMaker: Clear composition nodes on view attach

Fixes: QDS-10513
Change-Id: I3d2b1369c4e33fb6e21311c59a92625437382602
Reviewed-by: Qt CI Patch Build Bot <ci_patchbuild_bot@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

src/plugins/effectmakernew/effectmakermodel.cpp

@@ -168,6 +168,19 @@ const QString &EffectMakerModel::qmlComponentString() const
     return m_qmlComponentString;
 }
 
+void EffectMakerModel::clear()
+{
+    if (m_nodes.isEmpty())
+        return;
+
+    for (CompositionNode *node : std::as_const(m_nodes))
+        delete node;
+
+    m_nodes.clear();
+
+    setIsEmpty(true);
+}
+
 const QList<Uniform *> EffectMakerModel::allUniforms()
 {
     QList<Uniform *> uniforms = {};