Update Stokes Most

[gustavo-marques]

• Add new subroutine cvmix_kpp_compute_ER_depth to calculate the entrainment flux and corresponding depth using the entrainment rule. For each assumed boundary layer depth (OBL_depth) at cell centers, the subroutine iteratively searches for the first depth where the entrainment depth (ERdepth) becomes positive. The corresponding index (kER_depth) is also returned. If no viable solution is found, the subroutine returns ERdepth = -1 and kER_depth = -1.
• Add new subroutine cvmix_kpp_quad_fit to estimate the maximum of a quadratic fit.
• Update cvmix_kpp_compute_StokesXi
• Compute Shear, Stokes, Buoyancy, surface-layer TKE Production