Refactor code for use within interactive environments

[ewels]

Now that #1042 is merged, I think that we should be able to import MultiQC into a Jupyter Notebook and use sort of interactively. It would be nice to refactor the code so that it can be used for specific plots rather than only generating a big report, though I don't know how easy this will be.

• Make a new repository for an example notebook
• Get a basic notebook that imports MultiQC and just runs it on some data to generate a report
• Look into whether we can access results in the multiqc.report object
• Figure out whether we can print individual plots and result tables
• Refactor the code to make the above more intuitive
• Interactively add and remove sections using custom data (Jupyter Notebooks: Iterative running with custom content #2452)
• Write documentation

This could be quite a bit task with all of that, but would be good to get at least a basic run working.

[ewels]

This needs fixing for good Jupyter usage: #1141

[ewels]

Tightly linked to the refactoring described in #1790

[ewels]

Maybe related, just stumbled across https://github.com/olkuka/multiqc_jupyterlab/ - may be useful.