Add test capability for configuration options

[mmcky]

PR #72 will introduce the ability to compile a set of notebooks with and without a set of solutions.

However testing the configuration side is currently difficult as sphinx needs to be run based on a matrix of configuration settings. It would be nice however to have a test case for with and without solutions (i.e. two notebooks in ipynb references)

[mmcky]

See Issue #57

[mmcky]

• figure out how to test this with and without solutions (PR FEAT: Add support for solutions class #72) - through adjustments to conf.py.

Can we introduce a context manager? We will also need to know what to compare so may need to introduce a configuration matrix such that:

jupyter_drop_solutions = True  :  solutions_2.ipynb

otherwise we can generate conf.py from a template and use yaml for specifying a CI configuration set of tests:

A:
   sphinxcontrib-jupyter:
        options : { jupyter_drop_solutions = True }
        ipynb : {solutions_2.ipynb }

[mmcky]

@jlperla just moved your comments to an individual issue. Thanks for the writeup.