Support counterclockwise landscape

[chrisfenner]

We use pdflscape to rotate landscape pages on electronic displays while printing them as expected (i.e., without shrinking or cropping). The TPMWG asked for the .landscape option to rotate the other way. I thought this would be easy, but it is not an existing option of the latex package we are using.

Prior art:

https://tex.stackexchange.com/questions/699688/pdflscape-counterclockwise-landscape-with-section

Pull requests for this would be welcome, but I don't have bandwidth to work on this.