CONTRIBUTION: Turbulence - new kOmegaSST DES, DDES and IDDES model variants

- Initial code supplied by CFD Software E+F GmbH
- Refactored and integrated into the new templated Turbulence structure
  by OpenCFD

References:

- kOmegaSSTDES model:
  Strelets, M. (2001)
  Detached Eddy Simulation of Massively Separated Flows,
  39th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV

- kOmegaSSTDDES model:
  Gritskevich, M.S., Garbaruk, A.V., Schuetze, J., Menter, F.R. (2011)
  Development of DDES and IDDES  Formulations for the k-omega
  Shear Stress Transport Model, Flow, Turbulence and Combustion,
  pp. 1-19

- kOmegaSSTIDDES model:
  Gritskevich, M.S., Garbaruk, A.V., Schuetze, J., Menter, F.R. (2011)
  Development of DDES and IDDES Formulations for the k-omega
  Shear Stress Transport Model, Flow, Turbulence and Combustion,
  pp. 1-19