Draft: community/linux-openpax: base on main/linux-lts

I did this in !73325, because I thought perhaps there was something with how linux-openpax-dev was packaged that made my attempts at zfs-openpax fail. That wasn't it either, but since I went through that I might as well open this and see if it is of interest.

It didn't even want to start to build for riscv64 and I didn't get why, will have to look at that.

Basing off of linux-lts configs here, if you don't mind, I'd also like to look at some hardening configs that we may not want in a kernel for more generic use, with help and inspiration from community/kernel-hardening-checker - https://github.com/a13xp0p0v/kernel-hardening-checker