Replace linux-sigma APKBUILD with linux-lts or linux-stable and work on top of it

[rdbo]

linux-edge has security issues, as I pointed out here: https://gitlab.alpinelinux.org/alpine/aports/-/issues/16502
The APKBUILD I'm using is based off of linux-edge's, but I don't trust it anymore after finding out about those issues. Instead, I wanna replace the base APKBUILD with either the linux-lts or linux-stable one, and work it up from that

[rdbo]

Probably should redo linux kernel config also, avoiding too many modules and just using stuff builtin

[rdbo]

Builtins would fix the qemu UEFI issue also (i think)

[rdbo]

https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/85033
Should be good