Add download helper for ARM coprocessors

[virtuald]

Add something like what we do for the rio, maybe with some builtin profiles so it has the right flags? It would just be a wrapper around pip download.

Hm. I guess you could extend the installer to install to a PI also. That's probably not worth the extra effort, but the download step is annoying enough that it probably is.

[virtuald]

Inspired by https://www.chiefdelphi.com/t/how-can-we-install-packages-on-our-photonvision-orange-pi-5-plus/484615