Add an int min_prelude

[jonmeow]

The general intent here is to support basic use of i32 and similar integer types in min_prelude tests, without all the various arithmetic support.

This is in support of #5547 and #5549. However, I was originally asking for this to be reviewed as part of #5546 rather than either of those PRs, and I've retracted #5546 due to the discussion on Discord about test change complexity. So, to try to still get this in (and then merge the already-approved #5547 and #5549), splitting out this file.

Note this is actually the form of the prelude in #5549, which was adding negate -- it felt better to me to add that together as long as I'm splitting it out.