ENH: Added new nutUBlendedWallFunction

This forms part of what is termed 'automatic wall treatment' in the
reference:

    Menter, F., Carregal Ferreira, J., Esch, T., Konno, B. (2003).
    The SST Turbulence Model with Improved Wall Treatment
    for Heat Transfer Predictions in Gas Turbines.
    Proceedings of the International Gas Turbine Congress 2003 Tokyo

Note
    The full 'automatic wall treatment' description also requires use of
    the  Foam::omegaWallFunction with the \c blended flag set to 'on'