feat: add memory page size

[andre4ik3]

Adds memory page size reporting in bytes in the page_size field of CPU details. Technically page size would be considered a kernel property, e.g. on x86_64 and most aarch64 hardware it's 4096, on Asahi it's normally 16384 but hypothetically possible to be 4096, and on Ampere there are supported kernels of 4096, 16384, and 65536 page sizes. But since it's tied to the CPU architecture, it made most sense to me to put it under CPU details.

Example in a Linux VM:

[root@MacBook-Pro-2023:~]# getconf PAGESIZE
4096

[root@MacBook-Pro-2023:~]# nix run github:andre4ik3/nixos-facter/cpu-page-size | jq .hardware.cpu[0].page_size
4096

Example on an Asahi Linux machine:

root@athena:~# getconf PAGESIZE
16384
root@athena:~# nix run github:andre4ik3/nixos-facter/cpu-page-size | jq .hardware.cpu[0].page_size
16384