Make a function called write_io_data_to_zarr?

[jsadler2]

It might make sense to make a function called write_io_data_to_zarr or something like in the model_ready_data_utils.R that where we give it

• metab data
• do data
• inputs
• train/val sites
• output file

Originally posted by @jsadler2 in #78 (comment)