MOM6: Made 4 commits to support barotropic tides

  Made a series of 4 commits to help support the use of MOM6 in idealized
non-Boussinesq barotropic tide simulations, plus one follow up to correct
trailing white space.  All answers in existing test cases are identical, but
each of these 4 commits introduces changes to the MOM_parameter_doc files.
MOM6 commit Hallberg-NOAA/MOM6@87aeb27