feat: power operator with right associativity

[aljazerzen]

@max-sixty here is the right-asoc code

[max-sixty]

Great! I'll take it from here. Currently on my list after completing prql fmt

[max-sixty]

@aljazerzen although I had to fix a few things, and the order of math.pow is reveresed, this was actually very close already.

So I think ready to merge, have a glance if you can

[aljazerzen]

(I cannot approve because I opened the PR, but I am Aljaž Mur Eržen, and I do approve of this PR)