Setting WiFi blocked by other serial devices

[ButterscotchV]

If there are any other ESPs or other such serial devices, onboarding will get stuck when trying to set WiFi, as it tries to set the WiFi on the wrong serial device endlessly. This isn't super common but I've seen it happen quite a few times.

This can potentially be fixed by trying to set WiFi on all applicable devices at the same time? That would break the GUI though and in that case, we could need to implement a per-tracker progress bar and status. Alternatively, an easier but worse solution would be to timeout after some amount of time and switch to the next device instead.

This would also be a very good case for #1122 as it would be an easy workaround. I also am unsure whether the serial device popup is affected.

[Eirenliel]

Maybe we should combine it with provisioning multiple devices at the same time? Like when they're connected via a USB hub. I think it should send it to all trackers that are connected and display the state separately for each, like "Looking for new trackers..." etc etc