Create a mapping between code envs and projects/recipes

[hrjn]

It is often useful for a DSS admin to check where a given code env is used before updating/deleting it.

The goal here is to write a function that checks across all projects which recipes/notebooks/models/etc. leverage specific code environments. The output would be a dictionary mapping code environments to projects and project items, e.g.:

{
	"code_env_A": [{
		"project_X": {
			"recipes": ["compute_i", "compute_j"],
			"notebooks": ["notebook_i"]
		}
	}]                
}