adapter: Convert system config to unsigned ints

[jkosh44]

The system configuration variables were always strictly positive
numbers, but we were using signed integers to represent them. This
commit converts them to use unsigned integers.

Motivation

This PR refactors existing code.

Checklist

• This PR has adequate test coverage / QA involvement has been duly considered.

• This PR evolves an existing $T ⇔ Proto$T mapping (possibly in a backwards-incompatible way) and therefore is tagged with a T-protobuf label.

• This PR includes the following user-facing behavior changes:

  • N/A

[benesch]

Not that it really matters, but you might be able to avoid the expect with something like this?

let exceeds_limit = match u32::try_from(current_amount) {
    Ok(current_amount) => new_instances > 0 && current_amount + new_instances > limit,
    Err(_) => true,
}

Also, is this robust against overflows? It looks to me like if current_amount is u32::MAX and limit is u32::MAX the code (both yours and mine) will wrap around and erroneously allow the creation of the resource. Unlikely to matter in practice, because we likely won't have limits that large, but now that I've seen it I can't unsee it.

[jkosh44]

Yeah, you're right. I should be using checked_add here. I'll fix that.