Add tracer tendency terms and auxiliary variables

[brian-oneill]

Added functors to omega/src/ocn/TendencyTerms.cpp for computing horizontal advection, del2 mixing, and del4 mixing tendency terms for Tracers, and TracerAuxVars class to omega/src/ocn/auxiliaryVars to compute auxiliary variables needed by these tendency terms.

Unit tests passed on Chrysalis and Perlmutter CPU & GPU

Checklist

• [x] Testing
  • [x] CTest unit tests for new features have been added per the approved design.
  • [x] Unit tests have passed. Please provide a relevant CDash build entry for verification.

[mark-petersen]

Passes ctests on perlmutter cpu and gpu.