Refactor SafeWindowInterface protected data members to be private

As a part of the SafeWindow interface refactoring, the SafeWindowInterface class has 2 protected members that should be refactored to be private:

    std::array<QSafeRect, MaxDirtyAreasCount> m_dirtyAreas = {};
    size_t m_dirtyAreaCount = 0U;

For now they are suppressed for MisraC++, but they need to be fixed as there's no proper justification to have them protected.