Qt Remote Objects: Support setting default values of complex types in .rep file

// test.rep
POD Range(int min, int max)

class Device
{
    // Supported:
    PROP(int id = 42);
    PROP(QString status = "Setting X-range to {-10, 10}...");

    // Not supported:
    PROP(QList<int> targetIds = {1, 2, 3});
    PROP(Range xRange = Range{-10, 10});
    PROP(Range yRange = Range{0, 20});
}

class DeviceSimpleSource : public DeviceSource
{
    Q_OBJECT

public:
    explicit DeviceSimpleSource(QObject *parent = nullptr) : DeviceSource(parent)
    , m_id(42)
    , m_status("Setting X-range to {-10, 10}...")
    {
    }

...
}