Jest : The date-holidays debacle

[Laoujin]

In this repository: react-testing/src/date-holidays

Yes, this one was for a large part responsible for the performance issues from the "React Component Profiling" session but what is the fun in removing a heavy dependency when you are doing a session on performance optimization.
Now that is over, it would be cool to actually get rid of loading 10MB of JS for something that needs about 150 lines of code.

There is some code to get you started.

I would obviously be thrilled to have this merged into confac 😃
Bonus points for adding the tests & implementation in the confac repository, then I can just click merge!!

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