Deprecate / simplify 40 layer hardcoded bathymetry

[anton-seaice]

@TillRasmussen suggests :

If the bathymetry is split into a separate file then we should also consider where to put it. This is only used by the dynamics. Thus for this I would move data and function here and call it from e.g. init_evp.

The hardcoded 40 layers originate from the original implementation of landfast and it only relates to a specific NEMO simulation. This can probably be implemented more generic or the option can be left out. Environment Canada should be heard.

It looks like if use_bathymetry = .false. then the bathymetry variable will still get filled (probably with the minimum depth everywhere there is ocean).

But then the bathymetry variable is only needed if seabed stress is not .false. ?

So instead of the 40 layers, should CICE abort if:

• seabedstress is not .false. and there is no bathymetry file ?

[phil-blain]

We do not use the bathymetry file functionality with the seabed stress, instead we pass the bathymetry field directly from NEMO (this could be extended to pass the dynamic water height, but we haven't tried that yet.).

[TillRasmussen]

Some notes
In ice_init the value of use_bathymetry is output "if trim(grid_type) /= 'rectangular'"
Does this mean that it is not used when grid_type is rectangular
There are actually two versions of readers for the bathymetry.

Within ice_grid there is a choice of bathymetry_format:

1. default: reads netcdf or default to Nemo version
2. pop: reads binary or defaults to something else that depends on kmt.

Could use bathymetry be removed integrated into bathymetry_format with the following options:
nc (reads netcdf)
bin (reads binary)
pop (default from pop version)
nemo (if this option is to be kept).

I went through the different versions.
In addition to the use of bathymetry. This also influences dragio (drag between ice and ocean) through the surface layer if calc_io is true. The surface layer defaults to 2 meters if I read it correct.
Note that this is not done when bathymetry format is set to default and use_bathymetry is set to true. Is this a bug?