MPAS-A - Ensure consistency with some damping namelist variables

### What is the feature/what would you like to discuss?

The namelist variables `mpas_cam_coef` and `mpas_cam_damping_levels` both influence one type of damping that is applied to the top of the model (the absorbing layer) when MPAS-A is used as a dycore in CAM. If either of those variables are set to zero, the damping code is not executed.

The feature requested is to throw an error and halt when detecting an inconsistency (one variable being zero while the other isn't). The most reasonable place to do it is within the `check_user_input` subroutine of build-namelist. The message can state something like:
> ERROR: the setting of mpas_cam_coef and mpas_cam_damping_levels is inconsistent. Both variables either need to be zero or non-zero.

### Is there anyone in particular you want to be part of this conversation?

_No response_

### Will this change (regression test) answers?

No

### Will you be implementing this enhancement yourself?

Any CAM SE can do this