add a spec that will define the structure for the sugar config file

[xmnlab]

We need to define formally the spec for the structure for the sugar config file

Additionally, we need:

1. a documentation page with all the explanation about all the structure
2. we need a step that will check if the sugar config file has a valid structure

[xmnlab]

we can use this initial work as reference: https://github.com/osl-incubator/conda-on-air/blob/main/conda_on_air/conda_on_air.py#L26