Add arch to env API

[cdrage]

Is your enhancement related to a problem? Please describe

See: https://github.com/containers/podman-desktop-extension-bootc/pull/865#discussion_r1811037568

We have ways to detect windows, linux, mac

But not arch, we should be able to see if we are on arm or x86

Describe the solution you'd like

Addition to API for arm and x86 detection

Describe alternatives you've considered

No response

Additional context

No response