- `Pkt` was directed to `GName` to allow wall functions
     are usable by kkLOmega model
  - `Pkt` was changed to a non-const object, so that omegaWallFunc
    can modify `Pkt` at the wall, if need be.
  - Elementwise backward compatibility was checked by
    pimpleFoam/RAS/ellipsekkLOmega
  - New implementation was checked by changing omega:hole boundary
    in pimpleFoam/RAS/ellipsekkLOmega to omegaWallFunction