gpioctl should be able to switch pull-ups on if available.

[nettings]

As discussed at https://github.com/brgl/libgpiod/issues/31#issue-384105605 , libgpiod cannot currently do it, and it's arguably out of scope for a generic GPIO library until there is a generic universal kernel interface for this. But if we detect a Raspberry Pi, it would be a nice move to optionally set the pull-ups or at least bundle a tool to do it.