Convert primers to an R package

[schloerke]

... and submit to CRAN.

This will allow users to run the primer tutorials on their personal machines using the regular learnr mechanisms.

[Woosah]

I have packaged the primers into a rudimentary package for my own use some time ago. The only thing that I changed was to update the use of pivot_longer / pivot_wider instead of gather / spread. Up until now it is just a private repo without any extras and without documentation, description etc.
If it helps as a first step (on a longer journey up to a CRAN release), I am glad to provide you with the repo, i.e., make you the repository owner...

Kind regards!