[ClimaCoreTempestRemap] Support for terrain-warping in NetCDF output

**Is your feature request related to a problem? Please describe.**
Terrain export is not currently supported (https://github.com/CliMA/ClimaAtmos.jl/pull/536)

It should adhere to the CF conventions, e.g.
https://cfconventions.org/Data/cf-conventions/cf-conventions-1.9/cf-conventions.html#atmosphere-hybrid-height-coordinate

**Describe the solution you'd like**
Add method to `def_space_coord` that supports this. It may also require modifying how we internally represent the space.

**Describe alternatives you've considered**
https://github.com/CliMA/ClimaAtmos.jl/pull/536 does a quick hack to support it, but the results will not be correct (i.e. each level will have the same z values)

**Additional context**

Start by locating the `def_space_coord` method and inspect how space coordinates are internally represented for output. Read the linked ClimaAtmos.jl pull request and the CF atmosphere hybrid height coordinate convention before choosing an approach. Done means terrain-warped levels are represented correctly in the output and conform to the cited CF convention.

Written by the indexing model from the issue text.