feat: Add AGC Tools workshop code and cookie template

[matthewfeickert]

Add code that was shown at the IRIS-HEP Analysis Grand Challenge Tools 2022 workshop (c.f. https://github.com/iris-hep/analysis-grand-challenge/pull/51) (April, 2022) and use the scikit-hep/cookie template.

The code that went into the workshop example benefited from and builds off of code originally developed by (in rough chronological order):

• @lawrenceleejr's contributions to HistFitter in https://github.com/histfitter/histfitter/blob/master/scripts/harvestToContours.py (February, 2018)
• @lukasheinrich, @matthewfeickert, @kratsg in the sbottom likelihood PUB Note code (July, 2019)
• @lukasheinrich in https://github.com/lukasheinrich/lhoodbinder2 (August, 2019)
• @kratsg in https://gist.github.com/kratsg/4ff8cb2ded3b25552ff2f51cd6b854dc (January, 2021)

The goal for this project would be:

1. Make a Python library that is functional enough to be useful as a library in multiple use cases (i.e. have people build and extend on it)
2. Once it is sufficiently useful, work with @andrzejnovak to determine what, if any, parts of it might be able to be pulled out and refactored to work as a module in mplhep. The answer might very well be none, which is okay, but I would prefer to try to contribute to mplhep as much as possible to get the benefits of visualization tooling from all areas of the particle physics community, but we also don't want to throw everything that anyone has ever thought about before at it and bloat the library / add code that won't be maintained. (Think PRs are like puppies [video here])

* Add initial exclusion library interpolation and visualization code
   - c.f. https://github.com/iris-hep/analysis-grand-challenge/tree/61032a29db6d37d6cbc898e47e46ad1a94969751/workshops/agctools2022
* Add project template generated from https://github.com/scikit-hep/cookie

Co-authored-by: Giordon Stark <kratsg@gmail.com>
Co-authored-by: Lukas <lukas.heinrich@gmail.com>
Co-authored by: Lawrence Lee Jr <lawrenceleejr@gmail.com>

[matthewfeickert]

To ensure the name I've already pushed up the sdist built from this branch. So https://pypi.org/project/exclusion/ is this project :rocket: and you can already get the code used at the IRIS-HEP Analysis Grand Challenge Tools 2022 workshop that made this plot (mplhep styling is hopefully obvious :heart:)

from

python -m pip install 'exclusion==0.0.1'