Create integration test system for testing new compiler versions on many existing Gleam packages

[lpil]

[massivefermion]

Given the inactivity, I think it's better that more explanation is provided so that it's clear what the expectations are here. Do you mean a system that runs gleam test on multiple packages?

[lpil]

No design work has been done here yet. We need to have a think about this!

[cauebs]

I think he means something like https://github.com/rust-lang/crater