Add mock_snakemake functionality to clio?

[irm-codebase]

Is this suggestion related to a problem? Please describe.
One of the most annoying bits of using snakemake is the lack of proper debugging functions in most IDEs, slowing developement.

Describe the solution you'd like
The folks at PyPSA get around this with a 'mock' function
https://github.com/PyPSA/pypsa-eur/blob/master/scripts/_helpers.py

I've tested it and it works decently enough. Should we consider including it as part of clio-tools?

Additional context
One problem is that it requires snakemake to be 'embedded' in clio-tool dependencies.
This could cause conflicts when other projects use it.

Also, we should try to avoid 'fattening' clio-tools too much. Maybe this could be an optional dependency?

[brynpickering]

Could it be part of the data module template?

[irm-codebase]

Probably? It'd be repeated code in many modules, though.

Check here: https://github.com/PyPSA/pypsa-eur/blob/master/scripts/build_shapes.py
It's a conditional import under if __main__