Save more information about the configuration in `global_attributes`

[hdrake]

This is a good start:

https://github.com/ikeshwani/HorizontalConvection/blob/a4fdaf011aec2481f6dadc80029b8ea95a93afa0/src/simulation.jl#L278-L283

But other useful variables are: H, Lx, Ly; halo (or halo_x, halo_y, halo_z if you can't save a list as an attribute), the limits for x, y, and z, b★